Been thru a mostly similar situation recently so the memory is still fresh.

I think we can attack your issue in 2 aspects: thoughts and actions.

Thoughts: basically nothing much i can add than the resources already available to you and to do the right thing. I know it is hard because been thru all these but eventually you have to do the right thing so why not start now? One really important thing i realized for me is i was obsessed with what she represented which is totally different than the person she was/is. This helped me really start seeing that the person i loved is no longer here and the person her is someone i don't want to be involved with. I had to resolved this issue with myself to actually start to move on.

Actions: I won't bore you with all the easy to find moving on ideas from a easy google search, e.g. talk to your friends and family, distract yourself, etc. I have done a few unique things to give myself the closure i needed.

1. Donated to a children's charity in our names to honor our relationship and the things we were planning to do but didn't get the chance to do. this is to make our relationship has positive lasting impacts on the world.
2. Personally but may not apply to everyone, I tried to reiterate that she is choosing the easy but wrong things to do rather than the hard but right things. This is to give me the closure that I gave it everything I can and there is nothing much i can do.