You are NOT being selfish! He has a LOT of problems and hopefully, will be fine someday. But if he’s still sending you texts threatening to harm himself, he has a long road to recovery.
This is a LOT for anyone to handle, much less a young college age woman.
I understand why his parents want you to stick by him but they are only thinking about what’s best for HIM. That’s a very unfair, selfish burden to put on you.
Do you have anyone to talk to? Your parents or a counselor?
Also, does the rehab center or his family know he’s still threatening to kill himself?
He’s has control issues with you too, which is a huge red flag.
If you were my daughter or little sister, I would say put yourself first. I’d be very concerned about YOU and your happiness.
In just a year or two, who knows? Hopefully, he will be sober, healthy, more emotionally mature and maybe you two can work things out. Until then, focus on school and yourself. Again, you are not being selfish—-you are being smart.