I think GG's right that addressing some of the underlying sources of tension would help. It seems understandable that you might not feel in the mood or be prone to irritation.
I think I recall that you used to describe your husband as pretty well suited to you sexually. How much has your reaction to him changed?
Maybe it would be useful to change the frame for sex. You don't want to initiate, but it doesn't work right now if he does.
Could you schedule it, so neither of you is vulnerable to rejection? This would also give you the opportunity to get yourself in the mood a bit ahead of time.
Could you lower expectations? View it as a chance to build comfort with each other, or to please the other or just experiment, and find some value in it even if it isn't great? Attitude can make a big difference.
Would it help to just accept that you're not all that turned on right now? Not accept and therefore ignore it rather than trying to address it, but I wonder if you are fighting against that feeling and making yourself feel worse.
I think there was a bit addressing how to rebuild comfort in a book called "Because it feels good". Although that's not its overall focus, I think that emotionally it resonated with me when I read it.