Some advice?

hi, I have a situation with my girlfriend, she caught a chlamydia and she accused me off being unfaithful, yet I want and did the medical exam and was found out that I am clean. She have 3 kids that I love like my own and she clearly cuss me and use heavy word on me. I didn’t tell her yet about my result because I don’t know how to deal with my emotion right now… and just think about it make me really mad and sad, she already cheat on me but I disregarded that and forgive her but this time I think I will break up but thinking about those kids with no father and they see me as they own father… I just don’t know what to do. please help me with your advice.