Should I cut the thread or hope it holds us together

[StressedOut2]

My wife started seeing a therapist about three months ago and recently said she was diagnosed with BPD.  We have been married 19 years 11/12 months.  The significance of the time will come with the help I am seeking.  Five years into our marriage, my wife cheated on my with someone that was a friend.  The affair lasted 8 months, until I discovered it.  We went to a marriage counselor for almost 2 years, which ended when the counselor told me she couldn't help me.  I had and still have issues resulting from the affair.  A while after the affair, I would groan and complain about the affair and she told me she didn't want to talk about it any more.  I internalized my anger and frustration for the next 8 years.  (Affairs are my Achilles heal.  I expressed this to her before our wedding and she always replies that everyone says that.)  4 years ago, I went to a therapist to resolve an issue I with the relationship I was having with my son.  During the therapy, I realized I was holding my son partially accountable for the affair.  (My wife used to take him on dates during the affair.) The therapy made me realize I wanted a divorce.  I expressed that to my wife, she suggested we go to therapy.  Thinking there was a possibility to resolve the issue, I agreed. We went to several counselors during the last three years.  Approximately a month before we stopped counseling, because the counselor was going to help us develop a plan for a divorce, my wife finally came to the realization that she blamed me and my actions for her having the affair.  She stated that our marriage was on the rocks, it was horrible and that is why she allowed her self to have the affair.  (It didn't help the supposed friend of mine was feeding her lies to get her to leave our marriage.)  Even though she made the realization, there has been no responsibility taken by her.  Her apology is enough. Fast forward to April of this year.  She came to me and said she had been flirting with the husband of her best friend.  Pictures were exchanged, She mentioned to him that this would kill me, but not to worry because my bark is worse than my bite.  She hasn't wanted me to talk to anyone about either situation unless they are a mental health pro.  I think she is just ashamed, but I am not a PHD.  We have essentially cut ties with friends because I can't talk to them about the situation.
While i would like to blame her for everything, this is not one sided.  TBH I'm not going to win any husband of the year awards, but I wouldn't cheat on my wife.  She had been cheated on in the past and was also abused as a child.  I didn't leave the relationship after the affair, because I had a 2 year old son and she was pregnant with our second child.  (yes, it has been proven).  I wanted this to work, but I'm hanging on by a thread. She has never been violent or threatened to harm herself. The manipulation and projection are causing me to loose my mind. Everything tells me to divorce her, but I feel obligated to stay because of the BPD. I don't ever feel like I get to be happy.  I want to have a good relationship with my children and myself.  Thank you in advance for listening and appreciate any advice.

[RELATIONSHIP PROBLEM SOLVING]

RELATIONSHIP PROBLEM SOLVING This is a high level discussion board for solving ongoing, day-to-day relationship conflicts. Members are welcomed to express frustration but must seek constructive solutions to problems. This is not a place for relationship "stay" or "leave" discussions. Please read the specific guidelines for this group.