Husband won't leave me alone

I'm currently 25w3d along and have absolutely no sexual desire. This pregnancy has been really hard on me with a large amount of weight loss, extream morning sickness, epilepsy medication, a bad sciatica, and a nearly 2 year old. At the end of the day I'm in a lot of pain and don't want to be touched. It's gotten so bad that he's lucky to get it once a month and even then I'm not that into it. He guilt trips me all the time about it but I don't give in. Anyone else feel sexually dead?