Hi Myson and welcome to SR.
My AH went through a stage like this around our 17th year of marriage. He was comparing our relationship to a marriage he had seen grow out of a high school romance. This couple just seemed to flourish. He started to wonder what would our marriage look like if we had gotten together sooner. Then he started ruminating over at what point were we an official couple. This got him thinking and he recalled I had several other males in my life in the beginning of our relationship. So then I was being accused of cheating before we were even fully committed to one another AND 19 years after the fact. It was craziness. We had several blow outs and silent treatment sessions over it. Of course my H was drinking and not making sense at all. This whole questioning of crap so far under the bridge was very hurtful to me and made me extremely defensive. There was no way to argue over the past without sounding guilty. To this day my best guess is he has guilt over something on his own side of the street which caused him to witch hunt and blameshift.
Most ironically that perfect couple got DIVORCED over an affair soon after this whole blow up....
So you are hung up on your past. Go see a counselor ASAP. Talk it out. You are the one who chose to stay in the past and you are the one with a good life now.