Karen, I have been there too.
#1, You do not need a "reason" to not have sex.
If you dont want to, you dont want to. Period. Case closes. He can take a cold shower if he likes, not your problem!
#2)Of course you dont want to ,you are not alone in that thought process.
#3) Part of my boundries were that I would not engage in anything other than small talk if he was drinking. That led my relationship to the end (good thing) because he was drinking all the time, unless asleep. So who wants a partner you cant sleep with or talk to?
Boundries helped show me what was really transpiring in my relationship, becuase I stopped seeing through rose colored glasses, so to speak. What I thought I had, was an illusion.