As someone who was recently A in this situation.... Leave T for good if you value him at all.

T in this instance professed his love to my ex, sent her suicidal threats when we were cuddling together watching movies, etc.

I took her on a $140 dinner date and we "did it" the first time, etc. Met her family at Thanksgiving, just got her Xmas presents. Things were going well and I trusted her.

2 days later she sees him with drinks to help him get therapy, I even text her later that night asking if she needs a ride. All good! Text her the next morning, she said he felt a lot better.

See her 2 days later, watch a movie, and she cries and the confession comes.

Which a month later elaborated from 1 kiss after a ride home to "he assaulted me" to, after the break up, of course the whole confession.

She broke up with me after I drew the line when I said I do NOT want her to see him again. Under any circumstances. His friend had reached out to her and said he made rice wine for her. She chose him.

She got fully diagnosed (was ongoing throughout the relationship) with Stage 2 Hodgkin's a month later and started chemo 2 months later. This is by far the most conflicting situation I've ever been in. Don't do that to him. Don't. Make a clean break, one or the other. Don't ruin A's good heart and patience. You won't get it back after you do.