It is medically possible. The odds are meaningless if you're the one to get AIDS or HIV or any STD. Whether or not there was ejaculation, some sort of transfer of bodily fluids is still possible. The phrase 'probably' safe is meaningless. Clearly you want to know for sure.
When you have unprotected sex with someone, it's analogous to your having sex with every partner they ever had sex with. And, if they had unprotected sex with you, then chances are they've done it that way before too.
Get tested for HIV and tested for other STD. Never have unprotected sex again. It's not worth the worry, the risk and dying for. the same applies tyo hetero couples, too. Repeat the tests in about 6 months, as well.