Can’t tell my parents😪

Ok so I have been having sex regularly and it’s been protected. I’m on the pill and am very careful about it and I use condoms. I’m 13 and yes it’s young but that’s not what this is about. My boyfriend wants to have a threesome and I told him I’m not ready. I’m pregnant and I don’t know how. My boyfriend is very nice and doesn’t pressure me to do anything I don’t want to. He’s my first and only. I don’t know how to tell him or my parents. Should I stop having sex or get an abortion I’m just really confused and don’t know what to do. Oh and my doctor is my boyfriends brother so I can’t tell him either. What should I do?????