Should I talk to my son's girlfriends parents about birth control?

So my son is 16 and his girlfriend is 17. He has told me some pretty alarming things. Like they don't have a title on their relationship.. but after a year, I refer to her as his girlfriend. He then told me they act more like bf/gf than actual bf/GFS. To me that meant they are physical. I then started to talk about birth control... He then told me peeing after sex helps clean out the area from cum?! Literally I can not believe he said this. How could he even think that?! I am a very informative parent. I corrected him and said the truth that is for UTI prevention. He then mentioned how much the morning after pill cost and how he would get 50 dollars. Literally dying inside. He has condoms already from his (birth) mom. Says he is not telling me either way if he is a virgin or not.... Sooo now his GFs parents offer for him to sleep there all the time ... Very annoying... Even last night (Tuesday) my husband works overnights and my little ones 3 and 9 months go to sleep early.. the dad offered to drive him home then went to a neighbors and drank too much? Idk what to do, I think it's definitely time for the parents to talk .. idk why parents aren't doing this more often.. it's usually just let the teens figure it out and cross your fingers and hope they are smarter than their hormones.. I am dying to go knock on their door and just blurt out she's on Birth control right? A condom and the teenage brain with a frontal lobe still growing is grounds for disaster IMO. Seriously not sure how to approach this.

Side note: his birth mom could give two shits, she's a mom that wants to be a friend, she is a heavy pill popper, weed, and alcohol user (in front of any kid before it was even rec. legal in my state her judgement is very POOR and going to her is POINTLESS) I have always picked up the slack and will continue to do so.. more interested in my son and his GF not my husband's EXs mental state which IT is what IT is. 11 years later Ive already crossed that bridge just trying to explain for supportive feedback