I dont know what to do, please help = ' (

okay so im in a relationship with a guy who I want to spend the rest of my life with. we’re engaged and I’m havin his baby. Were both madly in love and I cant beleive that he’s mine. We got together over a year ago but split up for 3 days and got back together in february, then in june a horrible thing happened that I tried so hard to forget. I went to my friends house, he’s also my ex. but we were talking and then he was saying how much he missed me and how much he loved me and I hated the way he was trying to manipulate me by crying when I said I loved him too but in a different way. he was the one who split up with me in the first place. then he tried to turn me on and I pulled away but then he held me so tight, I tried pushing him off me but he was too strong and he forced himself on top of me. I screamed but no one came. I was soo scared. as soon as he let go I walked out . he followed and told me he did it because he loved me and that he wished it have never happened. he said he didnt want to lose me over this and that we should just pretend it never happened. I wanted that so bad. I felt so guilty for it happening I just wanted my boyfriend and when I saw him next I wanted to tell him but I was so scared that he wouldnt believe because he’s ex girlfriend cheated on him in the past and tried to blame it on rape. I just tried to block it out. I know its been so many months since but I just could never bring myself to tell anyone. im ashamed of myself for not being strong enough. what should I do ? I just want things to carry on as normal and I feel if I tell things wont but keeping it in is making me feel so terrible. I want my boyfriend to know everything but I dont want to tell him. please help ?