I had a foursome

I had a foursome 3 years before I met my current boyfriend and he feels weird about it. I told him in the early stages of our dating and he says he has tried to push it to the back of his mind since asking me to be his girlfriend but it came up again yesterday. He told me he feels like he looks stupid to everyone that knows about my foursome. I told him i feel slut shamed by him saying that. And he feels like this might be a dealbreaker but I told him this before we even made it official now it’s on his mind all the time and he doesn’t even want to have sex with me because of it.