STD talk with partner

i'm really concerned i might have clamydia and i am 80% sure i got it from my boyfriends ex. she's crazy and spreads rumors about my bf and i, but im hearing stuff about how she gave him clamydia. how do i go about having THE conversation with my boyfriend? might i add, the first month i was with him i had what i thought was tonsilitis but now, the more research i do the more it seems like sores. im young, this is my first commited relationship, and ive never had an STD before.