30M found my 30F DMs on IG

My BF was on my phone and went on IG and saw a DM from a rando guy I met once through my sister’s ex husband who was visiting from UK.

The guy was on my close friends story and replied to me saying “is that you” of me in an immodest dress and I said “yes lol” this is even worse bc my BF is conservative and the dress wasn’t. He was aware of the dress, but obviously not aware that other guy is seeing it.

When I met the guy, I was Married n would only post traveling or me and my husband or random politics stuff in my close friends so I kinda just added everyone on there besides family. He deleted or I guess deactivated his IG around my divorce time so I forgot he’s still on there. I think he only got it back in May this year.

I think my BF thinks that I’ve flirted with the guy, but i haven’t. How do I build the trust and show him that.

I’ve betrayed his trust by not only NOT removing the guy, but replying saying yes. Why the hell did I reply? Do I not love my bf? I’m insanely in love with him and don’t ever wanna lose him. I don’t know what to do now. He was visiting me but now we are long distance again.