What if he doesn't fit?

I am a very "petite" person.... not just in my dress size but down there as well. My boyfriend is coming down for christmas and new years and were most likely going to end up having ... only problem is is that im very small and hes really big... i haven't had in a very long time and honestly i didn't have a lot and it was still a little painfull for me. It's our first time as a couple and im scared ****-lesss to be honest... i want to so bad but hes so big he cant use regular condoms. and im xxxxs down there... how is this going to work? Help!?