It hurts to have sex. Please help.

So I guess I lost my virginity. In some way I don't see it like that because every time by boyfriend I try to have sex it hurts me too much I have to tell him to stop. He's 21 and I'll be 20 in two weeks. This weekend was the second time we tried. The first time we didn't used lube and it obviously hurt but he couldn't even get his penis in me because I'm too small and he's above average in size. At that time I was on my stomach and he was on top of me. This weekend we tried again and he was on top of me missionary and felt a pop. We think it was my hymen that broke and I felt a little sore. Twice after I used the bathroom a saw very little blood when I wiped. He tried again hours later but it still hurt me.

How can I get used to his size?

How can I relax my muscles and clear my mind so that I'm not too worried about the pain so i can actually enjoy It?

For those of you that also got their hymen poped, how did you deal with it afterwards?