Some guys can be funny - afraid that a little snip around his bizniz is going to turn him gay?? He'd rather have you risk your health with an unwanted pregnancy in your 40s just so he can do it without a condom? He can't ejaculate while wearing a condom?? Getting your tubes tied will make you want to cheat?? Boo-frikkin'-hoo. Any old excuse will do, as long as it gets him what he wants. He has a major problem between the ears that's causing him to have these problems in his pants. Having your tubes tied is not going to give you the urge to cheat - your husband sounds extremely insecure about his masculinity, almost to the point where I'm wondering whether he may have been sexually abused as a child.
You should be able to sleep in your own bedroom and say No to sex any time you don't feel like having sex - for him to assume that he has the "green light" is wrong and devalues your equality in the relationship. It just shows how selfish, ignorant and déclassé he is. Why should he call all the shots and control your sexual relationship? I'm glad you're starting to stand up for yourself and are making plans to leave him. Nobody needs that kind of uninformed bullcrap directing their life. That attitude might have flown a couple of centuries ago, but in 2008, it is simply unacceptable.
You aren't doing your kids any favours by staying in a relationship that revolves around chauvinistic ignorance - you don't want them to think that this is "normal" do you?
If you're done having babies (and by the time you're in your 40s, I'm hoping that you are) then having your tubes tied is the best method of permanent chemical-free birth control. It can be done first thing in the morning, and you're on your way home a few hours later. You ache for a couple of days afterward. Effective for birth control immediately (vasectomy is usually deemed effective after a 6-months post-op follow-up sperm count of zero).