Scared to say no

I am separated from my husband, and its been horrible for the last month. I became more serious about cutting him off when I found out he had hacked my phone account and was spying on me. Admittedly I was talking to an old flame, and he confronted me about it. I was disturbed by how he found out, and said I no longer wanted to try with him. The last month has been a barrage of insults and attacks. Last week I ran out of gas and this week I got scammed. I called him both times. I wanted help with the gas, but not with the scam. However, his response was it was it was my karma. I called my adult son and he brought me gas. That too was something he attacked me over. Saying I put my son in danger. Since the gas incident he has said things like, he is a child of God and I keep messing with him and thats why bad thing have happened. That I am someone who has always skipped accountability and so I deserve this. Also that these things happened because he wasn't there to protect me. Last night he told me that he had a peri rectal abscess. This is his 3rd one. The first burst on it own and the second one he convinced me to lance. However, this is a serious condition, usually brought on by ulcerative colitis (he hasn't sought any diagnosis or treatment). He should be getting it surgically drained, getting antibiotics and finally treatment for the UC. Here's where I might be the AH. I started saying back to him that its his karma. That he deserved it; basically everything he was saying to me over the last week. Late last night he asked me to come over and Lance it. I dont want to for a slew of reasons. Including that he will be alone in a snow storm after I do it, at risk for sepsis. I know he is seeing if I am willing to help him. At one point I asked him if he would bring gas to me, and he made it clear he would but he would also continue being mean to me. I continued to seek help from our son instead and afterward said I was relieved he didn't help me. Now I am scared to say no. Its a test and these things become a way for him to get me back in his circle of influence. But if I dont, he will have a reason to keep being mean. What do I do?

TL;DR: my narc husband wants me to do a home medical procedure after having saying bad things are happening to me because I am not being good to him. I want to say no, but I am scared he will continue to harass me.