How do I deal with her.Should I let go of her once and for all? I can’t take too much stress.

So, we have been together since half a year or more. My only condition to her was even from the beginning that she never lies and cheats. Cause we were dating to marry. She did, multiple times and maybe overall 5-6 times. I caught her every-time. But I was deeply in love, so i forgave her, but not the last time when she did the same again in December. So long story short, since then we are on a rough phase. I long to be with her, i love her enough be with her but I do not trust her anymore. And ik i should have blocked any contact with her but we tried to be friends, but it doesn’t work. I will end up being rude and eventually she will end up crying and i will feel guilty. I feel she has changed, but my brain says no, just dont go back at any cost! She told me she’s waiting for me till march, if i dont decide to be with her, she will let go of this. Now this is scary, i am very emotional, and now m confused about it :(. Please guide me, is it still worth giving it a shot? Or once a cheater always a cheater? And at the same time my parents gave me a deadline to marry by next feb, so it’s stressing me out