That list is very good list! Good for you to write it. Without going through each thing I think there is defintely some good reasons to work on the marriage.
Your post after that makes a lot of sense. We learn behaviors or reactions to behaviors from our parents. There is no blame here since they only taught us what they were taught. Your mother sounds like the martyr, fixer, rescuer etc. I think you already picked up on part of that you might have inherited from her.
All the more important that you commit to working on YOU. This pattern could repeat itself. (I am guilty here) Look through your list and ask yourself "what do I have control over?" Anythiing that has H in it is a NO. If you think you can control it you are going to be the enabler like your Mom and we know that is not healthly for Lola.
The answer to some of your fears or questions will come to you when you go through this process. Your Dad's unresolved issues from previous relationships?? Remember my words about my 1st W? The spoils of unhealthy, unresolved issues are all around you.
Focus on Lola. Get Lola healthy. Lola healthy = right decisions for Lola. Fears will go away. Truth will be revealed. The right choices will be made. Forgiveness will have happened. Resentment is gone. Your life will not be scarred by this.
My goal is to some day be the person my dog thinks I am