AITAH for turning down sex from my wife

For the past 4 years, I have been in a sexless marriage in my 30's, maybe 2-4 times per year. My wife attributes it to her antidepressants and medicinal marijuana that kills her sex drive and I've tried to be as supportive as possible but with no resolution in sight, it's causing me to become increasingly emotionally detached. Which upsets her. I've tried explaining that the lack of intimacy for so long is the root, but she gets defensive and says it's not her fault she has no desire anymore. So I live my life frustrated and take it whenever I can, as infrequent as it may be. I have a high sex drive and fantasize about cheating but I know I never will act on it. One of the few events that turns her on is weddings. She likes to sneak off in the middle to a secluded area for a quickie. Lately it's the only time I can rely on getting any. Well we're attending one this weekend. I've been turned down so frequently for so long and harboring so much resentment as of late, I plan to refuse her advances. I already know it will be a huge blow to her self esteem but I'm over having it be on her terms only. AITAH.