So I recently feel like I am at a crossroad with a long term female friend.

We met in uni and had a close bond, however through the course of the years she betrayed me. I don't care much for it now, but to put it in context my friend hooked up with a guy I was seeing without me knowing after witnessing her flirt openly in front of me to later find out that she went home with him one evening when I wasn't around. I did confront her at the time and asked how this was ok, she however dismissed it and didn't see it as an issue because we were not dating.

I distanced myself for a number of months after the incident but we went back to spending time together again without ever touching on the subject again so it was not ever truly resolved. I chose to reduce our time to only having coffees and occasionally hanging out as she would behave mostly like this around alcohol and social environments.

Although recently I am faced with the awful feeling of her making advances towards my present boyfriend whom I am very close with and share a really good relationship with. I have kept her away thus far but we recently went out for my birthday and I got irked to see her pull the same type of behaviour with my present partner. She has been forceful in wanting to be a part of my relationship and wanting to get to know him but I absolutely feel horrified to integrate her into my life at that personal level as she can be flirtatious and oblivious to her behaviour even though I have spoken to her about this.

Where the conflict within my psyche comes in is that a year ago she offered me to take her place at a job that she no longer wanted and I took her up on the offer. It was a great help and I feel incredibly grateful for the good things she has done for me, however this issue that I have seen in the past has resurfaced and I am finding it to be unbearable to witness. I trust my boyfriend 100% and he has zero interest but I am mortified to have her in my personal space again because it is uncomfortable and inappropriate of her. I have only witnessed how this is an integral part of her personality and she won't change.

I am wanting to severe the friendship but am I being ungrateful for the good things she has done for me or is this just unacceptable behaviour on her part?