I know it's hard for both you and your husband, dilemmas whichever path you choose; but because this is the matter of end of life, I think it's the time to put yourself first before anyone, everything has an end and it's now your end. It's not wise to force you to go through so much pain that only you can feel it for the sake of anyone else's well being, including your loved ones.
Yes, your husband must grieve then, he can be in shock, terrify, feeling loss and cheated etc all negative feelings; think that your husband is a responsible adult he will survive his love for himself and you. He must also think of your well being. Will he be glad to know you're at peace? Will he let you go if he knows you're no longer suffering? He may accept your decision and still love you the way you are.
Please don't take my words as encouragement for you to CTB; This is to tell that you have support which ever decision you take, there's no right or wrong here, there is no single "right" way to grieve and it's very humane to deal with it, it is life and death as it is; It just have to be accepted. After all, acceptance is great friend of mental health.
Let yourself feel the moment and express it to your loved one, don't mask it too much so you can't be seen as yourself again. It's also important to leave a closure so your husband can cope in a healthy way.
Life's a ride, you can change anytime you want.