HELP! Painful Anal :(

My boyfriend and I have wanted to do anal for so long. We have had a small bit of success, he got off once this way, but it was so uncomfortable for me and was so sore after I nearly cried. WE'VE TRIED EVERY THING. We have insane amounts of lube, I've used a vibrator, he's used fingers first, I've relaxed to the max. But every time he gets in almost half way it feels like something is literally tearing. It feels like friction on a cut so he has to stop because I'm in unbelievable pain. He does have an above average penis but it's nothing crazy! What do we do??