Good job on going to the movies with your brothers. That's a step towards detaching. And its good that it pisses her off. Let it. Keep working on your detaching; you're not there yet. Dropping the rope and detaching isn't about giving up. Its about not letting them control your emotional state by every little thing they say or do. You're still in that place so keep working on it. I know how you feel. I know how sick the thought of losing your W makes you. But its not until you truly let them go and are willing to walk away that you can begin to save your M.
Me: 48 y/o W: 47 y/o Together: > 20 yrs BD: Dec '15, then S 2nd BD: Mar '16, then I filed for D April '16: started piecing