I just want to see what people outside the situation think.

Ok my boyfriend and I broke up on the weekend. We'd only been officially "together" for a couple weeks, but have known each other for 14 years. I am madly in love with this man have been for years. So I need objective opinions.

Before me he was on and off again with his ex of just under a year. She was abusive and constantly cheating on him. Well she had a bit of a mental break down when they broke up (police removed her from the home, she was admitted to a mental health facility. Well she got released on Friday (dec 4th) she showed up at his house, and him being nice let her in. You can see where this is going cant you? She took a shower and came out naked, she was obviously trying to seduce him. He slept with her. Ended up having her removed by the police again a couple days after that cause she showed up and lost it on him (I dont know details) and she is back in the hospital.

He didn't hide it from me, he was upset and texted me saying I deserve better etc but wouldn't tell me what was wrong. I went over to his place and he confessed, told me everything that happened. I cried, and ended up walking out cause I just couldn't look at him without breaking. Well now its Thursday and I've been a mess since. He has said all the usual things "it meant nothing" "it was a stupid mistake that he immediately regeted" etc ... he accepts his responsibility in it (she didn't even know about me).

I being a b%#/@, gave him the ultimatum of me or her. I would work past this with him, but she had to be out of his life. He said he won't cut her out because she needs someone right now, with her current mental health state so he won't stop talking to her, but won't see her in person.... So I walked away.

My opinion is yes shes in a bad place, I understand he doesn't want to abandon her when she needs all the help she can get, and prior to him cheating on me with her, I had no issues with him being in contact with her. I would have been happy to stand by her with him to get her help. But he betrayed me, and lost my trust.

Am I doing the right thing by walking away? Or

Am I being selfish and jealous?

Are your gut feelings always right?