If you are 100% certain that he is not your one, then you need to be gentle but honest. I am going through a similar thing but it's my husband who is not happy with me. The good thing is that there are no kids. If you think there is a chance, then try to find it, but it not, the sooner things come out, the sooner you both can begin to live a happy life.
Keep us posted. Good Luck.
I would just sit him down when he has time to talk and just spit it out, without blaming, accusing,
I doubt your husband would be surprised if you said you weren't happy. It doesn't sound like he is either.
I'd get my legal ducks in a row, i.e. consult a divorce attorney and learn your rights and responsibilities, and go about setting up a separate bank account, scouting your own place to live, etc. It sounds like the biggest fear you have is not keeping your cats.
Hopefully you and your husband can part amiably and without a lot of harsh words.
Only one way to find out...and that's tell him.
Thanks everyone for the advice and reassurance!