I feel lost...

My relationship is at rock bottom, due to things that have happened in the past.. I made mistakes 2 years ago while my boyfriend and I weren’t together. But today the past got brought up and I know he is hurting and it kills me, because we have 2 kids together and I’m pregnant again with our 3rd but do things I did, I can tell he is unhappy he says he loves me and forgives me but I can see how much he is struggling and I can’t help but cry and feel like worst person known to man kind. I feel like I can’t even be happy about our baby that’s growing inside me. I don’t know what to do