I don't know what to do 😭

Long story short, I've been with my boyfriend for almost a year and a half. We have sex regularly, like an every day thing, and have since about 2 months into this. On Dec 5th, I was sexually assaulted, by someone I thought was one of my best friends, while my boyfriend was at work. I never told him bc I didn't want him to look at me differently. 😭 I found out I was pregnant 3 days ago. Now I'm conflicted bc all this time of me and my bf having sex, nothing, and I get assaulted and now I'm pregnant but I'm not sure if I want to keep it bc I'm not sure who the father is. The "friend" has a type of cancer and is on medication that supposedly makes his sperm count lower than what it already was. He use to be married and it took him and his ex awhile to concieve bc he already had a low sperm count. I had a mediator reach out to him and he said he's almost positive it could not be his for that reason. I go to the doctor this week. I'm just confused as fuck on what to do.