Can we still use our band name after the singer quit the band?

I am in a band that has just broken up. Basically the singer quit the band to pursue another music path and said we could not use the name. There has been no contract made up and there is not a trademark on the name. He is not going to use it either. He just does'nt want us to have it. We have several months worth of shows booked under that name. The singer is threatening to take all the band members through civil court. Can he do this? He is very mad because we decided to keep the band going only after he offered to give us the name. This is such a mess. Any insight would be helpful.