Worried about false memory of cheating

I'm hoping someone can help me as I really feel at the end of my rope. I'm 26 weeks pregnant and was over the moon when we found out. In the last few weeks I suddenly started worrying incase I had cheated on my husband and my baby isn't his. I would never do this to him but these thoughts won't go away. We were both at a wedding around about the time I conceived and I'm worried that I can't remember cheating due to alcohol. I remember most of the night and don't remember even speaking to anyone who wasn't our friend. I keep thinking I would have been devastated on the night and the next morning but then my head goes back to thinking that I may have blacked out and forgotten about it. It's got to the stage where I have created a whole scenario in my head and I can't enjoy my pregnancy and feel I don't even want my baby anymore. Can anyone help?

its not atypical for ocd to first hit or become extremely heightened with pregnancy. with women, pregnancy or childbirth is often the event that pushes them into seeking treatment. have you had ocd before being pregnant?