My girlfriend’s (21F) parents is forcing her to break up with me (23M) because they found out we were sexually active and I don’t know what to do?

My girlfriend (21F) and I (23M) have been together for a year and a half now and have been sexually active since 3 months into dating. We obviously dont tell both of our parents this but yesterday, her parents found a pack of condoms while cleaning her room and were very unhappy with us. Her parents had a discussion and ultimately told her that she is not allowed to date me anymore since she’s living under their roof and their rules are no sex. She can’t afford to move out and neither can I especially in this housing market. My girlfriend is reserved person who cannot confront anyone without crying or breaking down.

I on the other hand feel extremely betrayed as I always frequent their home, 2 or 3 times a week and built a (what it appeared to be) a healthy relationship with her parents. Whether it be making dinner, going out to bars with the dad, helping her mom do chores, etc. I just feel betrayed because I thought they approved of me. But apparently they dont.

We both don’t know what to do and we spent hours trying to come to a resolution but we cant. We were talking about seeing eachother in secret but are afraid they will find out. What are we supposed to do?