I can't seem to drop the boiling anger I have.

What are you angry about? How are you going to express it?

I can't seem to drop the resentment/entitlement.

What are you entiteled to?

I'm wrecking my M because I can't seem to be the man that I need to be for myself and for my W so that she has a rock against which she can get her sh!t together.
I disagree with this statement unless you are having another A.
Dont worry about your W getting her shtuff together. Thats her job. Work on yours. Thats a big enuff job to handle. Its not going to wreck your M. Thats why you said...for better or for worse...at least that was why I did.

An individual, cant wreck a marriage, you can only have people who quit.

How can she trust me when everytime she tests I slip?

Thats her choice and problem too. Your still overly concerned with her reaction.
Why dont you let her beat you up when you slip, instead of beating on yourself? I didnt manage to reconcil with x by beating on myself about what I did wrong.

You cant implement a boundary if you dont believe you are worthy of it.