It's definitely NOT stupid and we're NOT tired of hearing from you - most of us read our story in what you write and on some level we can relate. I love your planned out conversation! Very clever. I just started getting in to alanon and really working the steps, so you probably want advice from someone with more experience. But, for what it's worth.... take the emotion out of what you want to say to him. It sounds like you are angry (and rightfully so!) and are acting on that anger. That's not good for you or for David. I'm reading the Alanon's 12 steps and traditions that I picked up at a meeting yesterday. The second steps says we act irrational and we shouldn't - we should give it over to our higher power and let him handle it. I don't suggest having a long emotional conversation with David, especially since you are working so hard to detach yourself, but don't act out of anger. You are better than that.
It's not a fun situation to be in, so hang in there.