Sorry if this is long, I'm hoping for some advice from people who have perhaps been through this.
I will preface that I have OCD which I'm currently under treatment for as of recent, I obsess about things, especially in relationships.
I met DP when I had literally just come out of a LTR with an emotionally and physically abusive manchild, I dated him 16-20 and so it really affected my view of the world. I seemed to take out the behaviours I learned from my ex on my now DP. I was very controlling, irrationally afraid of him cheating and imposed horrible controls over his life. I tried to stop and I received counselling.
At some point in our relationship (we have now been together 6 years) DP began using an anonymous chat site as an escape, this escalated into anonymous sexting with random women. I found out a year ago. I logged into the site on his account to read messages etc. and see what it was like. I actually laughed and was quite relieved, I found it all a bit pathetic, it was a bit of an alter ego and he used it for advice in the relationship as well as definitely sexting with strangers. He remained anonymous by name etc. but they sent pictures he told me (I couldn't see these as he deleted them every time to ensure they weren't stored I guess).
After I found out he didn't really beg or deny, he came clean, he went to therapy. He said the therapy didn't really help him in some ways but did allow introspection and he feels slightly stupid but also thinks the risks are not worth it. He has definitely shown a lot of change - his phone use is around 30 minutes a day, he doesn't use safari or anything (as this was how he used the site) and has now given me control over his life which is probably not good for me - as a result I am seeing a therapist to try to move on with the feelings.
As we are young and because of circumstances, I decided to try to forgive. I have mostly good days but I am sometimes riddled with anxiety. The anxiety comes from the 'what ifs'. When I thought something was up and he was doing something wrong, every small unexplained detail in the world I would analyse. This would be silly things to more obvious things. I have been wrong more than I have been right. However, when I caught DP he told me the truth about a lot which explained a lot of loose endings I have.
Now every so often I will think of an unexplained thing in my mind and start trying to understand it, i.e. 'does it mean this?' and I will never get an answer. But it throws me into anxiety. Before I found out he was doing anything the same effect would have occurred if I'm honest.
I need to leave it in the past and move on, then if it happens again that will be it. But I keep thinking of unexplained events which if they are related to the wrongdoing then it's irrelevant as it doesn't actually change the story.
Does anyone have advice?
p.s. I'm pretty certain no physical cheating occurred. I also used to check his phone regularly (something I've stopped with therapy) since day dot and he was never using his number to speak to people. I also don't think any of his sexting could constitute an emotional affair.