The horse is out of the barn -- if he wasn't 100% on the bus with a vasectomy, you and he should have held off on it indefinitely.
You and he still have differences regarding the size of your family. You do not wish to bear any more kids; he wouldn't mind it if you got pregnant again.
The 2 of you are also not exactly a couple of carefree millionaires. YOu are wise to want to forgo having a larger family.
Did he also think over the option of banking his sperm before surgery? Maybe he'd have been all for the surgery had he banked his sperm; that's only my guess.
I suggest counseling. Do it now before some sort of a blow up and rift occurs in your marriage. YOu mentioned advanced ages, you're the only breadwinner and you do not wish to have any more kids; how about how you feel about more kids? Didn't he take that into consideration?