I have a disease): help!

I found out today that I have chlamydia, and when I told my boyfriend he said that the last person he had sex with (obviously besides me) was freshman year (we're now seniors), I should be good with the medicine they prescribed but because he's had it for such a long time he might be facing higher problems, how can I comfort him? Since he kinda hates himself right now, and he feels so bad that he's even being kinda of distant with me, honestly even a bit rude, but I know this isn't who he is, I know his just really mad at himself, so what can I do? Besides telling him that I'm here for him, what can I say or do?