My past and my SO now....

My SO has a very bad habit of bringing up my past and then making himself sick over it. See, before him I had a FWB for about 1.5-2 years and made the mistake of telling him when we first got together bc he had asked me when I had had sex last and then who with. Well apparently he was very disgusted by this and said that I should have had more self respect for myself than that.  I was just trying to be honest with him from the get go and now I have to pay for it every time he brings it up. I make it a point to tell him that it bothers me and upsets me very much when he brings it up but then he doesn't want to talk to me bc he makes himself sick over how disgusted he is with the fact that I had a FWB. Idk what to do. He says he loves me and wants to be with me, but I don't understand why, if that's true, he lets something I did in my past bother him so much. He isn't speaking with me at this moment and I believe this is why. Idk what to do. I love him so much and it makes me sick at my stomach that he gets this upset over something that doesn't matter anymore bc I am with him and only him. What do I say? What do I do? I don't want to lose him over something so stupid... I'm so upset right now... 😢😢😢