Should I forgive her or Should I end that relationship or?

Am in a university third Year and am staying with my childhood friend who is now my girlfriend and she’s in second year in the same university with me,in our home we are not well-off this makes life difficult for me since am still a student,but to the lady’s home they are well off.So my girlfriend pays almost 90% of our bills eg rent,food and others.The remaining 10% I normally search during weekends when am not in school through small small hustle.

We’ve dated for almost 3yrs now,So recently I realize that my girlfriend I’ve been cheating on me with another man,She normally pretends that she’s going home to see her parents unfortunately she ends up in thats Man house even for even a week,The man knows very well that am leaving In the same roof with this my girlfriend although I’ve never met him, he’s pacient waiting for our break up so that he can take full control of my girlfriend according to their charts that I view on my girlfriends phone.
The man knows very comfortable that we are sharing this lady and he is comfortable with it but to me am not comfortable coz I can’t share my girlfriend with some knowingly,I can rather release her at peace due the respect I gave her.

When I asked my girlfriend,she admitted and she asked for forgiveness saying it was not intentionally,She also told that she has no problem with supporting me coz she know that am capable of doing better in the coming days.
Am confused, I don’t know what to do,So my question is should I forgive her or End the relationship??? I need help

End it. It’s good that she admitted it and apologized, but she knows what she was doing. She obviously gives him enough reason to believe that you’ll break up so he can come in. I would just leave & find someone who loves and respects you.