I'm now getting depressed, which makes me worry that I'll eventually say something to her - which of course would start the sex argument and the whole process would start again. I still plan not to say anything, but when I get depressed I have a hard time hiding it, she asks me what's wrong, and I eventually let loose.
Hi Sooner, All of this builds up inside and you're going to let loose. What would happen if when she asks you calmly said that you are hurting because of the lack of affection. (Notice that I didn't say NO affection.) Then continue to say that right now you don't want to discuss it because your emotions are wound too tight, but, if it's ok with her, you would like to discuss it later when you have more emotional control.
What this might accomplish is to get it off your chest in a CALM way, admit to a current emotional weakness on this subject (hey, we all have our special buttons!), and, with her approval and agreement, leave the door open for future conversations.