Im not sure I'm just a pussy or if this is something that needs to be thought over. Am in a LTR for about 10 months now. My best friend was killed in a car accident and LTR was the only one who helped me get around and process this.

However, 2 months after his death, I found out she's been fucking around with her ex a month into our relationship. Had no plans of telling me. Both deny they fucked but she lied before so I assume they did. I let it go (my mistake, I understand that now) because of mentioned tragedy and I feel like I'll have nobody left. I am considering ending it and I feel like an asshole for waiting for so long. How do I go about this?