Just over three years ago, Jill Bettelley risked her life to save her baby when he was given 48 hours to live.

That fragile, helpless little boy has now grown up into a mischievous, loveable child with laughing blue eyes and a baby-toothed grin.

And today, Luke Bettelley is preparing for his first day at school - a day his mum feared would never happen.

As she prepares for the big adventure, Jill feels a sense of wonder at the little boy's progress.

But her happiness will be overshadowed by a bitter, gnawing sorrow.

For Luke's dad will not be there to see his youngest son off on this milestone day. From now on, he will not be around to see most of Luke's milestones.

After almost a decade of marriage, Dave Bettelley has come out to his wife as gay. He has left the family home in Arundel Road, High Salvington, to live with another man, although he denies they are having a relationship.

On the Friends Reunited web site, Dave has announced to his old schoolfriends at Durrington High School: "I am currently divorcing my wife and have decided to bat for the other side - that is, I am gay - a shirt lifter or anything else you wanna call me. I guess that will probably shock a few people but who cares - I am what I am. In any case I am happy and having fun!"

The news confirmed what Jill had suspected but it still came as a terrible shock to the woman who is desperately trying to hold her family together and carry on.

Just as Luke grows up into the little boy his mum and dad didn't dare to dream he might become, his whole life threatens to fall apart.

The family home is on the market and his parents are about to embark on a legal battle over mortgage payments. Nothing will be the same again.

Jill said: "Dave is having the time of his life, meeting new people, going out to gay clubs, having fun.

"It's like a second childhood. I am here, holding everything together, feeling like my entire married life was a sham.

"I've got two brilliant kids but at the end of the day I feel like our marriage didn't mean anything to him."

The day Luke was given 48 hours to live, Dave and Jill clung to each other with the desperate love and grief of parents who believe they are about to lose their son.

It was a love that held them together as they watched Luke fight back from the brink of death and learn to walk, speak and smile again.

But the strain of their son's illness and the weeks they spent in hospital, the worry, the exhaustion and the constant need to put him first eventually tore the couple apart.

Now Jill knows she will have to save her son for a second time - this time from a broken heart.

"Luke is too young really to understand why his dad isn't here anymore but he knows things aren't right.

"He sometimes cries and says 'where's daddy, where's daddy?' and I don't know where to begin explaining to him what has happened. I don't even understand it myself.

"I didn't think things could get any worse than they were when Luke first got ill but these blows just seem to keep on coming."

It was early spring in 1999 when Luke first got sick. He had been diagnosed with suspected hepatitis at Worthing Hospital and then whisked to King's College Hospital, London.

Doctors there told a baffled and terrified Jill and Dave that their son's liver had failed and he had only hours to live.

Jill said: "It came totally out of the blue. One minute he was fine and the next he was dying. We thought when he went to King's they would make him better but instead they told us he was probably going to die."

Desperate to do anything to save their son, Jill and Dave begged the doctors to help.

With no other donor available, the only option was for one of them to donate a part of their own liver. It was an operation never before done in the UK.

Jill said: "Me and Dave were both compatible but I wanted to do it. I felt like Luke was part of my body already.

"I had carried him for nine months, he was so much a part of me. It was only right that I gave a part of myself to him."

The doctors warned Jill that she could die too but she felt she had no choice.

"I wasn't scared for myself. I was told it was a very high-risk operation but I never thought I would die. I knew I had to survive so I could be there for my children."

Luke was under the knife for a gruelling 13 hours as parts of his mum's liver were transplanted bit by bit into his tiny body.

"The day of the operation I went to see him to say goodbye. He was covered in drips and looked so ill and so little. I gave him a cuddle because I didn't know whether I would see him again.

"My operation went first, then Luke's. I didn't come round for about four days. I was in intensive care while they operated on Luke, completely unconscious. As soon as I opened my eyes, I had to see him, had to know how he was.

"I was on morphine drips, the doctors were trying to stop me from sitting up and I was just saying 'I've got to see him, let me see him'.

"I was in agony, crying from the pain but it was wonderful to look at him breathing and know he had made it through.

"I used to ask myself why it had to be Luke but then I told myself at least he had survived and at least I had been able to give hope to other families in the same situation.

"I always thought every parent would do the same but the doctors said that wasn't true. I have another son Kyle, who's eight, and I did have to think about what would happen to him if I died. But there was no time for 'what ifs'."

Luke made a remarkable recovery. His illness left him with permanent brain damage, which has slowed his development and caused a speech problem. But today he is as boisterous, curious and friendly as any other five-year-old.

Jill said: "Luke has a place at the Palatine School in Worthing, which teaches kids with special needs. I think he will get the attention he needs there.

"He has been going to the Camellia Botnar Children's Centre since he was three and they have made so much difference to his speech. Before that, he couldn't tell me he had a belly ache or if he wanted a drink.

"It seemed as if he had locked himself away after all that had happened to him and was shutting everything out.

"I felt like he had built up a brick wall to protect himself from the world and I just wanted to hammer that wall down.

"The day he starts school will be very special. There have been times when I have wondered whether it would ever happen.

"With Luke, I have to take every day as it comes. His body could still reject the transplant at any time. I will never stop worrying about him.

"But part of me is sad that he is getting so grown up so quickly. I will have a little cry when I wave goodbye to him at the school gate.

"I suppose the next big milestone will be his 18th birthday or his wedding day. It's really hard to imagine that.

"Still, it seems like no time since Luke's second birthday and christening, which was the first big milestone. That was such a happy day. We were all just so happy he was alive.

"Now that memory has been spoilt because I wonder what Dave was really thinking, whether he really wanted to be there."

Dave said: "It's great that Luke is starting school. I'm going to be really proud when I see him in his little uniform.

"I can't stop thinking about how lucky he was then and how fragile he still is now."

Dave was not keen to go into details about the relationship break-up. He said the important issue was Luke's first day at school, not his decision to come out and live a gay lifestyle.

Jill agrees. On September 9, she will put everything else aside to make it Luke's special day.

But she cannot escape the feeling that her son's life has been torn apart once more.

And she can't forget that she will now have to face an uncertain future on her own.

She said: "It used to be that we were a team, that we worked together to build a life for our kids. Now I have to be the strong one and cope alone.

"I feel like a lioness protecting my cubs. I would do anything to protect them. That's what keeps me strong."