I believe that all posting here are trying to support you, even if that means that they will point out where they think you may be going wrong.
Many of us have had partners and husbands leave us for someone else... And eventually many of us realised that the time spent evaluating the OW's level of responsibility for the pain we endured, her appearance or her morals and trying to compare these to our own was counterproductive in all sorts of ways.
When we are that hurt, it is nearly impossible to accept that the relation was fulfilling for the one that left -for whatever reason- and that when they had a chance to extricate themselves from it they did.
Heaven knows I violently cringe when I look back at how I lost all dignity when someone I loved deeply and for ten years left me -ghosted me in fact- for someone they had impregnated, except I only found that out from a family friend, once the baby had been born months later.
The fact is, he did not leave me because they were going to have a child or because she was better or worse in any way, he left because the relationship he had with me did not meet his needs. The end.
I know that now, many years later but it has only been three months for you and you have conducted yourself with great poise and dignity. I admire you for that!
You are going through an unavoidable process, but consider the experiences of others, if you can, and the comments that point out truths that differ from yours -like bluntness'- these are well intentioned and helpful.