Hi, I myself am recently separated and spend most of my time with regret, thinking of mistakes made in my relationship.

I can relate to not being understanding, caring or loving enough. A helpful resource for me has been "Emotional Intelligence for Dummies". A handbook for people wanting to understand empathy and adopt it into their everyday lives.
The idea of a book telling me how to care more seemed insulting at first but in started resonating after a while.

I always seem to be told how I put my feelings first, and only seem to understand after its too late. I hate apologizing for breaking my family's hearts when I know with some thought and in the moment mindfulness, I could have validated their feelings and made a step toward a better relationship.

I hate myself when i make bad choices and that prevents me from loving myself which in turn prevents me from loving others...

I think I share the same personality change as you described ( I feel broken).

I hope this resonates somehow for you.
BUT....

Don't Give Up! Light a candle in your darkness, keep asking and looking for help. Maybe spontaneousness and more positiveness will help you both find the love that brought you together. If you do love her, show and tell my friend.

Show and tell.
Good Luck