HELP! Can't remember....

Okay so this may seem weird but I really need help trying to remember a particular mini drama series that aired in the UK about 8-12 months ago.

I think it had 3 parts to it. Each an hour or an hour and a half long. It was a mystery drama. It was about a woman who's husband had just died and she had suspicions about his cause of death. He died in a car crash and they found another woman in his car and their friends and family all assumed he was having an affair the night he died. His wife just didn't quite believe it so she decided to take matters into her own hands and investigate what he was up to in the last few weeks of his death. She made a big diary of evidence as to his whereabouts every day. She even went as far as going to his work and looking at his emails and finding out who the other woman was. She was completely alone, no one believed her, they just thought she was in denial. But as she began to put the pieces together, she got entangled into this big cover up and she did in the end discover her husband was in fact not having an affair and it all ended happily ever after.

I need to know the name of this series, I can't for the life of me remember what it was and can't it on the internet. I am almost sure it was on ITV1 but it's no longer on the website. Please help!!