Help! Making Love With My Friend's Girlfriend Is Making Me Go ‘Crazy’

A man has begged relationship expert, Deidre for a way to overcome a situation after he betrayed a friend’s trust and slept with the girlfriend.
I was a shoulder to cry on for a mate’s girlfriend but we ended up having mind-blowing s*x. Now I can’t stop thinking about her. She’s a friend of my sister’s so I see her fairly frequently. Her partner is a drunk and always down the pub.

She is only 23 and has two kids. I am 28 the same age as her partner. I know he gets violent when he has been drinking so I worry about her. She was in a state that evening and texted me after they had a massive argument. She was waiting at her front door as I arrived, so I gave her a hug.

We fell asleep on the sofa after talking for an hour or so. When I woke up, she kissed me. It was a full-on kiss with her grabbing the back of my head and pulling me towards her. We moved to the bedroom and the s*x was great just how I’d always imagined it would be.
I felt guilty afterwards as her boyfriend is an old friend we went to school together. But the next time I saw him, he told me he had slept with a girl he met in a bar that night.

He and his girlfriend are very unhappy together and he treats her really badly, but she won’t leave because of the kids. I don’t want to confess to my friend and make things worse for her. He has hit her a number of times and could do it again. But I cannot just walk away as I feel I need to take care of her.
She says she wishes she had met me years ago. I know I have done wrong but she is constantly on my mind. I try never to be left alone with her but I don’t know how long I can control my feelings.

@uptimistpeters