Pregnant by Fwb. Should I tell him?

My period is 5 days late now, i am extremely nauseous all day and can’t eat anything without gagging but I’m waiting till Friday to take a test. I’ve been seeing this guy for a couple months now and I really enjoy the relationship we have. We both have daughters mine is 2 and his is 18 months and he has full custody of her. I think I’ve made up my mind on getting an abortion if I am. I just don’t know if I should tell him. I don’t know how he would react or what he would want. Should I tell him? Should I just go through with an abortion and not tell him? I don’t want to ruin our friendship but I also don’t want this to cause problems later on.