I’m such a bad person....

I’m almost 20 weeks pregnant and I honestly don’t know if my boyfriend is going to be the Dad. When we first got together I was coming out of emotionally and mentally abusive relationship where I always got cheated on. I let that happen for almost 5 years before I was done with it. I met my boyfriend now and I shouldn’t have gotten into a relationship as quick as I did... My birthday is the beginning of October, that weekend I went out to drink and the next morning when I woke up my pants were unbuckled and I already know what happened.. I haven’t had the heart to tell my boyfriend because he’ll want to know every detail of who was there and who it was but him and I weren’t even together this particular weekend. I just feel like I can’t tell him now. I don’t know how. I will be so heart broken if it’s not his baby but there’s nothing I can do.. 😔 him and his family are just as excited for this baby as I am..