I had sex with my boyfriend a few times while he had poison ivy (or sumac/oak) on his penis/genitals. will this hurt me internally?

Refrain Until Cured: Developing a rash from any of the plants you listed on the penis/scrotum should be treated as a serious complication. However, assuming he washed before you had intercourse for the first time, there shouldn't be any concern on your part. He likely will need treatment and i would suggest (for his sake) refraining from any more intercourse until the blisters are gone.