Crippling guilt

I am suffering from crippling guilt following a sexual indiscretion I had in Feb 2013. I am happily married but one night in Feb I got very drunk and was talked into having sex with a prostitute by a friend, I really didn't want to but when drunk am easily led and went ahead with it - in the end it was my decision, I should have stood up for myself and just left. Afterwards I became obsessed that I had an STI, I had to get tested repeatedly, and paid for several online tests to prove to myself that I hadn't caught anything. One week after the indiscretion my wife found out she was pregnant, I became convinced that I had passed something onto her and the baby. I now accept that I don't have an STI as all tests came back negative.
Now however I am racked by guilt over betraying my wife. I love her so much and now I think I have ruined my life - she doesn't know what happened, however I know what I did, and I just feel so dirty and ashamed. I think about it every day and I think in a way I am punishing myself, but I can't stop it. I keep thinking about the night I went with the prostitute and how dirty and sordid it was. I keep feeling incredibly guilty and just go round in circles. An easy way out would be tell my wife what happened, but advice I've had from friends is not to as it would destroy her and make her incredibly sad. I think the best way would be to just keep this to myself, but I can't seem to get on with my life. It is now affecting my work and my sleep. Can any advise any techniques for dealing with guilt??

If you were my husband... I would not want to know (especially not during a pregnancy or once I've had a child w you!) and I would want you to put it behind you and move on. Never do anything like it again, but I wouldn't want my husband to really suffer over something like that. Move forward and try to forget.

Agree with rooben.
Most people have done something really stupid that they bitterly regret in their life, because few people are perfect.
You made a mistake, you feel remorse, just make sure you never do that again.
Make up for it by being the best husband and father you can be.
And cheer up! You got a baby on the way!

Thanks guys for taking the time to reply, I was a bit nervous when I posted as I wasn't sure what kind of replies I'd get back, but your posts were v helpful. I have decided, as you both suggested, not to tell my wife. There's no point hurting her unnecessarily and during the last week or so I have finally (!) started putting this episode behind me. I made a big and v stupid mistake but we are all human and I have learnt my lesson and I think paid the price in terms of months of worry. Have cut down my drinking and am now looking forward to the arrival of our baby in few weeks time, and spending my life with my beautiful wife. Onwards and upwards!

I'm happy you're doing better and it sounds like you have really learned something from it.

My husband decided to come clean to me about every bad thought/thing he had ever done. In reality, I had done worse myself and certainly had similar thoughts. But you really don't want to hear that crap when you're pregnant, and maybe not ever. He felt much relieved after the Congo, but it took me years to get over it. So, yeah... just move on!