Your story breaks my heart. I am so sorry to hear what you and your kids are going thru, and to have an unsupportive husband on top of it all.
Flossy gives some really solid advice. Morally, philosophically it is a quandary in terms of treating your kids surreptitiously w/o your partner's knowledge. I'm not saying you would be wrong to treat or not treat them without his knowledge, I'm just saying I wouldn't want to have to make such a decision! Maybe you can start treating yourself first and see how things go?
I do think it would be great, if possible, if you can find friends or family members that you love and trust to help give you guidance and support through this. Regardless of your husband, this is all a lot of heavy stuff to deal with on one's own, and the treatment process will probably prove long so would be great for you to have people you can lean on.
Thoughts and prayers your way. Also, you are not a bad mother. I am sure you are a terrific mother, who has been dealt a very very difficult hand. Infectious disease is tough, please don't blame yourself.