Your W DID try and get a separation (divorce?) agreement in place when she sent you the house paperwork but you told her you would not sign it or look at until the house sold. She made it perfectly clear she did not want to continue the marriage in a legal sense but you refused to get the agreement in place!
So, you basically told her you would not give her what SHE wanted until things went the way YOU wanted. I understand you were trying to buy more time but it was all about control. Had she gone to an attny and filed the agreement you would have NO CHOICE but to respond. Instead she at least tried to be a bit more gentle about it. And I am going to guess she has seen this pattern in you for a LONG time and the financial disaster from your business was her breaking point. Honestly, WE all see that pattern and I do think in a gentle way it has been pointed out to you many times.
It is VERY cruel for one spouse to just dump the other spouse. I don't think anybody can or will debate that point.
Her leaving was NOT all about the financial mess. It was patterns of behavior on BOTH your parts. She could have gotten help or used resources to try and change that but she chose not to.
Your W has been behaving badly for a long time yet you didn't feel the need to expose that - now though that another man *might* take her to dinner you are up in arms. Her being a childlike adult that can't deal with anything is far deeper a problem then dinner with a man.
You were afraid to rock the boat. I get that. I did the SAME thing for a long time and it resulted in me getting so emotionally steam rolled I wasn't sure I would EVER recover. You had many avenues to take but you let fear stop you. So what can you do different now?