It 's been on and off for 10 years. Me 48 her 39 1 son of 9 years old, two proposals for getting married accepted by her, but a life in rollercoaster and sometimes police involved

(as many Nons here) that was causing me to leave (thinking that my absence would make her think better, as I didnt know about BPD then).
Last time a year and a half i left ( i now know I caused her the abandonment issue), cause couldnt stand her outbursts and wrong accusations in front of my son who was suffering inside and caused him alopecia. i left for my son's health and living on the same building top floor. Even went for some dates with other women, but wasnt feeling like being free to move on.
So, recently (last May) and after some time together we had due to our son's and his football tournaments, i asked her if we could be together again and get married straight away, for her to feel secure, not like the previous times that delaying the wedding was causing her all these outbursts being insecure.
She denied and said that she got sick of depression the last time we separated and doesnt want to get thru this again. I understood but wasnt convinced. I thought she needed time. She indeed showed some interest, was telling me 'she wish things were different but was very hurt' etc.
Ofcourse she never admitted her mistakes that were causing the stress in our household and onto our son.
All her closed girlfriends have been discarded by her as well.
I continued trying to pursue her, without any further results and then decided to see why and found out she is in a r/s with a divorced man over 50 y.o with 2 teenagers, which was hiding to me. Last month I saw that he even goes to her home with my son being there and i got stressed much more and confronted her with names for this.
After all these and the three months trying desperately to pursue her with long texts, sometimes being very loving and sometimes with nerves due to her denial- she admitted she is in a r/s that she feels she is being respected, i told her that i am moving on, decided to go NC and contact only for our son.
I am a wealthy man and can offer her and my son the security they should have. I also love her and told her many times. I even financially supported her for some bills lately!
My questions are:
1. Does she, or will she ever consider a priority the creation of her family for our son that loves too much(that was her dream with me all these years) and finally leave her r/s that counts 6-8 months as i guess?
2. Or with BPD's the only think that count is present feelings and considering that she is into this r/s 6-8 months, she is still in the honeymoon stage? Don't they think rationally at all?
3. I'm shocked, as to why she prefers an old divorced man, than the father of her son and her true love of the last 10 years.
4. I guess I shouldnt wait for her break up and move on straight away?
5. Wouldn't be easier to get her back if she wasnt a BPD?
6. i know she loved me very much and was showing this till the beginning of this year! Is it possible for her feelings to dissappear all of a sudden and shifted to her replacement?
Your answers will much appreciated.