Suspected OCD, not coping well

Sorry in advance if this isn't the place for this. I'm brand new to 7Cups. I haven't been officially diagnosed with OCD, but I've been suspecting it for years now, and this past month has been extremely hard and made me suspect it even more. I'm bringing it up when I start a new therapist this week. I'm sorry if suspected diagnoses aren't allowed here. I don't mean any offense, I came to this conclusion after looking into actual symptoms and other people's expreinces with OCD, not just stereotypes.

Without going into all the details, coming clean about a lie has triggered a huge episode that's lasted a month so far. I confessed to my partner about some crappy things I did when we first started dating, but I told him in pieces because I was a coward and tried to convince myself I didn't need to tell him everything. I eventually did tell him everything because the guilt/anxiety was eating me alive, but now my brain is TORTURING me over any little detail about it. I have a bad memory, so I fogot some things. Some were big and felt important to share, but others were inconsequential. Some don't even have anything to do with him or the situation, but I can't function at all until I confess everything. Even something as small as remembering I did a certain thing three times instead of the two I told him makes me think "you're a bad person, you're a liar, you don't deserve happiness because of what you've done." The confessing feels so compulsive, like I can barely stop myself. I don't want to tell him anything else, it's putting such a strain on the relationship, but I can't stop. I've barely been able to eat this past month because the stress is ruining my appetite.

I don't know what to do. I've had horrible luck with therapists (my last one said my mental health is because I'm following the wrong religion) so I've never been in therapy for very long or gotten any help from it. I'm starting with a new on on Thursday, but I don't know how to cope in the meantime. I've looked up some tips and articles but everything says to just let the feeling pass. But even if I deal with it until it passes, it always comes back later, and stronger. I know this is my fault. I feel like I deserve to be tortured, but it's so scary in the moment and I panic. I'm sorry this is so rambling, I just don't know how to make it better.