I had a similar thing happen. Me that 2 other guys started a band (bass, drums, guitar). We soon realized that we needed a good singer since neither of us sang really well nor wanted to. The drummer knew a lady and pulled her into the band. She was very good and just what we needed to step it up a notch. Well her husband came along as part of the deal. He played a little guitar and sang a little. Both his playing and singing basically sucked.
Well the first thing they did at our band meeting was go through our song list and toss most of our songs and add her songs. That was no big deal because we were eager to learn and she was a great singer. Though it did bother me a little.
Then they changed the name. The band became HER NAME and the WHATERVERS (it changed many times but her name said the same and first.) We that got on my nerves a bit because I felt they hijacked our band. We the leader (her husband) told me in not so many words that we are nothing without her. He was bit right so I shut up and went along with it.
Next thing I know we have an additional keyboard player, 2 back-up singers, sound guy, etc. Also every time I come to practice he has bought more equipment....of which the band ends up buying.
Here is how the gig pay works. Everyone gets a cut of the pay. The person that brings in the gig (her or him) gets another cut and the PA gets a cut or two. So essentially him and her get 1/2 or more of the gig money. This really cheesed me.
So the first person they fire is the drummer that brought them into our band in the first place! I get let go 2nd.
Since then they are semi-successful but have had a revolving door of personnel.
I feel sorry for the keyboard player because he knew her a long time and they were friends, but not anymore. Also this was the height of the keyboard player's musical life. He has been trying to recapture that glory ever since.
Moral of the story is: Husband/Wife teams are to be avoided at all costs!
PS: Later I did join another band with husband and wife, but the wife was only an occasional player and mostly was busy taking care of the kids.
Sorry, but this sounds like some cats didn't have the cajones to stand up when they needed to at the beginning of this. It was as simple as: "Sorry, _______, but we hired you not your husband. He ain't cutting it. So it's a no go with him. If you don't want to be singing with OUR band without him... well, we'll just have to work it out with another vocalist. We would've loved to have you but not if we have to change everything around to have you."
Then find another vocalist.