You should have left the thing with the loan from her dad like this:
"I paid him $2500 of the final $4000. I do not feel the other $1500 is my responsibility." And left it at that.
When she launched into her reasons for D, listen and validate. Then after a few minutes make an excuse for why you have to go. I know you said you listened and validated, I hope that is true. Because if you pointed out your changes....REALLY REALLY REALLY bad move. This cements in her mind that you are only showing changes to try to save the marriage and that you haven't really changed. People that really changed DO NOT GO AROUND SAYING THEY'VE CHANGED. People that want people to think they changed go around saying it.
They dwell on the negatives because it fits the narrative for what they want to do. No one ever has said "My marriage was so good, but I want to end it!"
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018