Major POCD feeling very distressed

Hi, some of the posts on here relate to what I've been going through. About a year ago a very disturbing childhood memory came into my mind and it's causing me a lot of distress.
When I was about 13 or 14 I pulled down the pants of a younger child to have a look. I would say the other child would have been about 3 or 4. I didn't touch him and as far as I can recall I pulled them up again straight away.
I've spoken to my doctor about this and also received some counselling which helped for a while. But it came back quite strongly a few months ago so I went see a cbt therapist. He diagnosed me with OCD and he made a lot of sense in terms of how he described it.
But a couple of things really continue to bother me . One is the age difference- until tonight I thought I would have been no older than 11 or 12, but I worked out tonight that I must have been older (based on who I was friends with at the time). This has totally floored me, I've read some stuff that basically says that such an age gap puts in the abuse rather than exploratory play category. I feel physically sick and extremely distressed at this new realisation.

I also obsess on why I wanted to be around a child of that age. I do remember that my friend had a younger brother and, as crazy as it sounds , I really wanted one too. My siblings were much older than me so to them I was just a kid who got in the way. So I remember thinking that having a younger brother would be quite cool.

I was never sexually aroused around this younger child but I do remember wanting to be in his company, I suppose looking back I felt confused to be honest. Ive never had any interest in kids in that way, I'm married with kids of my own and don't have any POCD thoughts towards them or any other kids.

I guess this has now taken over my life, it is with me all the time. I try to use the technique of thinking about other things but it works only briefly. Today has been a really low day with the age difference thing. I just wish I could go back and tell my younger self to stay away from that kid. It's affecting my home life too. I try to carry on as normal but when I see my wife and kids having fun I almost feel jealous. I've spoken to my wife about it which wasn't easy and I have another cbt session next week. It will probably be my last one as they are expensive and I've told my wife that I'm feeling much better so she'll wonder why I need to keep going back.

I feel totally ashamed at what I did, I was old enough to know better. I worry that I might have harmed that young child, but I feel exhausted, stressed and frightened. I don't really know what I expect anyone to say in response, but I just thought I would share my story. Thanks