I messed up big time. How do I get his friendship back?

If he is a true friend he will eventually forgive you. Do you have serious feelings for him? If you do maybe you should tell him. But if he is gonna be serious with this other girl then just leave him alone because you don't want to just be the girl on the side. What if she really is pregnant, that would suck. I would definitely just leave him alone. I would just give him time to think because he probably has a lot on his mind and may be scared. Like I said if he us a true friend he will respond to you.