TW abortion. Halp. please dont judge..

Soo... I've been with my boyfriend for two years, weve know each other for 7.. anyways.. I slept with someone else and my bf in the same week that I was ovulating (no excuse but we were blacked out in his car) and just found out I'm pregnant, 4 1/2 weeks along I told my bf but not the other guy. He was insanely calm and I told him I'd have an abortion since there a chance it's not his and he agreed... im 27 I have a 7 y/o now and the other guy is 6 years younger than me.. I feel like I should tell him even though that's what I've decided but at the same time I only decided that for my actual bfs sake and the fact that we are barely getting by rn as is.. I have always been pro choice but I'm not sure I can commit to this abortion.. and I know my bf will probably leave me if I dont have one.