It sounds to me that your issue is not so much with playing the bass itself, but with playing bass for a band which is not giving you any spiritual reward. I've been there - I quit the band. Not an easy decision but I found my lack of enthusiasm was starting to poison my relationship with music itself, and not just that of the band. There's no need for it to be unpleasant and you might even get a nice farewell gig out of it!
After leaving the band I never stopped playing as such but found it a bit uninspiring to sit at home and play unaccompanied. It's difficult when you're used to playing with others, particularly with a great drummer. After about a year or so I ended up depping for a mate's covers band and am now the full-time bass player (I say full -time, our gigs aren't as frequent as we would hope!). It's just covers, classic rock and pop, but it's great to play out of the comfort zone, and it's great not to have to bash heads writing material all the time. And needless to say it's a wonderful feeling to have a roomful of people up and dancing to a song they know and love.
Of course it may all pan out differently for you but I honestly think the first step is a clean break from your current situation. Onwards and upwards.