Hi LIL,
Welcome to MB. So sorry for all you've been through, but you have found the best place possible to help save your marriage.
Your H is manipulating you, holding you hostage with this "trust" nonsense. Trust is earned. Period. Once it is violated, it can be restored, but it has to be earned back. There is no way an adulterer can demand trust. It just doesn't work that way.
I am no expert, but there are a couple of things that leap out of your post:
1. Your DDs don't know half of what's going on. Yes they do. They may not know the details, but they know something is not right. By not stopping this destructive pattern, you are teaching them a terrible life lesson.
2. With each A you would wait for "big changes". You don't get anything by waiting. Nothing. You have to stand up for yourself, and your girls, and tell your H what you want.
3. Your H says "he might as well have the A, because you don't trust him." This is childish, manipulative, cake-eating behavior. If one of your DDs said, "I drank alcohol because you don't trust me, so I might as well do it anyway", how long would you put up with that?
There are a lot of issues here, and not the least is your H's problems with addictions - Pain medication, ephedrine, methamphetamine, possible sexual addiction (?).
First, I would move this post over to General Questions II, because there is a lot more traffic, and you will get a greater response. There are a lot of "old-timers" here who can share their expertise.
Go get a GYN check up and get screened for STDs. Tell the MD/NP you want to be tested for everything - syphillis, gonorrhea, chlamydia, herpes, HIV. Every time your H has had sex with another W, he's put your health, your life at risk. And, by the way, he has to go, too.
Buy the books - Surviving an Affair, Love Busters. You can get them from Amazon.com, or any bookstore, Heck, the libraries even have them.
Consider calling Steve Harley for counseling.
Are you sure your H is clean from drugs/acohol now?
You have a hard road ahead of you, but maybe coming here is the miracle you were praying for.