Gave her Chlamydia & Genital herpes

My cousin (17) has been with her boyfriend (18) for about 8 months now. About 4 or so months ago, she went to the hospital after showing symptoms (but wouldn’t they have shown earlier? Not 4 months later?) and found out she contracted Chlamydia, obviously from him. He claimed that he didn’t cheat and that he must’ve “unknowingly” already had it before he met her. Of course she believed him and she stayed with him. She didn’t even think it was a big deal because pills can make it go away 🙄 I told her that she’s lucky it wasn’t HIV but she shouldn’t downplay it either.

Now he has given her genital herpes. She’s been hospitalized for two days (and will continue to be for a few more days) because on top of that she has other health issues as well. He claims that he was born with herpes and again, that he didn’t know. Of course she believes him.

I don’t know a lot about Chlamydia or even Herpes, so I’m here to ask. If he was born with it, wouldn’t she have contracted the herpes a long time ago?... Not 8 months later? Her doctor is also telling her that if she has kids, there’s a 50/50 chance that they’ll be born with Herpes, is that true? Also, do you believe his stories?

Btw: They had unprotected sex from the very beginning because she does have the birth control implant to help regulate her periods. I tell her to use condoms but they were FWB before dating so I guess she trusted him. I doubt him because he was very recently (like a week or two ago) caught sexting another girl, so who knows where he got it from.