what would you do/believe?

So I've been married five years and I am pregnant with second baby. And it hasn't been easy I was diagnose with ovarian cancer at 29weeks I'm 33 now and it's been hard to grip on to. I had thought at one point to leave my husband and spare him this pain. I know horrible idea well his mom convinced me to do this with him by my side as he love me and is my support. He cried and begged me to let him be there and I broke down I was afraid I am afraid of not making it and I don't want to take him down with me.
Well we finally decide we would get through this. Anyways today he got home from work had a bad day. So I rubbed his shoulders asked if he was hungry he gave me attitude sayin no I just ate after all day cause I didn't have time till the end of the shift. I said oh I'm sorry we'll go shower and take a nap relax. He snapped at me againsaid omg can't I just sit for a while. My feelings were hurt I didn't do anything wrong I just wanted to help. 
So I left the room and started watching dishes after I was done I was just wsnting to leave as my hormones were getting the best of me and he walked up and tried to hug me I dodged him and walked away to get my keys he's like fine whatever I won't hold u. He's like your not going to talk to me? I answered him saying why should I so you can snap at me some more? He's like I had a bad day can't you have some patience. I'm like I didn't tell you to go clean or help me do something I told you to go relax. And he just rolled his eyes and left upstairs. He came back an hour later changed and saying he had to go back to work and just walked out. I found it odd that he had been home two hours but just now had to go back.
He didn't come back till two hours later. I was furious no text or anything. 
And on top of that shortly after he walked in I started getting harassing message from some chick he works with saying she was sleeping with my husband . Calling me fat and ugly. I was ignoring it brushed it off till she mentioned my condition and how they couldn't wait for me to die so they can do their fling without hiding it. Note besides my husband mil and my parents no one knows I have cancer. So that set off in alarm. Do I believe her? Why would he share something like that ? If he wanted to leave why didn't he just go when I told him to? Idk what to believe but it's awful to think my husband is one cheating and two isn't man enough to leave me cause I ill? What's worst telling some hoe im dying ? 
Idk what to believe I just grabbed my daughter and left no clothes or anything just what I'm wearing amen purse I texted him once I found a hotel and told him I didn't want to hear his explanation or his denial of it cause how else would she know about my situation so screen shot the messages and send it to him I asked for a divorce and that I would get my things tomorrow while he was at work