My best friend has a girlfriend that he thinks he loves. And I am pregnant with his baby and I think I am in love with him how do I tell him because he sayshe love me too what do I do and how do I tell him?

The last thing you want to do is just come out and say you are pregnant cause then it is all about him feeling obligated to you and everybody thinks you used getting pregnant to entrap him. Discuss with him about his decisions and how positive he is about what he wants in life.
But you need to let him know as soon as possible but you both need to talk things out first.
Most times when a guy is with a girl out of obligation to the baby it doesn't work out. They feel entrapped, obligated and resentful especially when they had somebody else they WERE with.