Guilt is an interesting emotion, isn't it? Some people are easily shamed and others have cast iron hides.
Don't feel bad about your situation not turning into a full blown one-with-the-lot disaster. It's all out of your control; you can not predict any of this stuff and neither can anybody else.
You also have limited agency over other people. Sounds like your husband made a decision based on how much guilt he was willing to wear if your news had been different and he wasn't there with you. Either way, one of you was going to feel like shit.
These things pass. Feel what you are feeling, have a good look at those emotions, know they are valid then try to park them on a shelf somewhere for a while.
If you find you are still struggling in a few weeks time, or feel that you are really getting dragged down, think about seeing a counselor. Cancer, as you say, is cancer. It has a lasting impact. Mxx