water in exhaust, mechanic said needs head gasket

Just bought the used Rendezvous, yes it has pretty high mileage on it, but it was all I could afford. I've only had it 2 months, when while approaching an intersection, it stalled out, and the temperature went all the way to high. I was able to restart it, the temp returned to normal.

I was fortunate to be close to home .On my way, Ii stalled one more time, and I was able to restart it again.

I called my mechanic to let him know I will be having it towed there. After a few days, he informed me it had water in the exhaust that indicated I had head gasket problems!!! He refused to work on it and told me to sell it as quick as possible!!