After you repair your ridgeline with some low stretch cord with a breaking strength of several hundred pounds, try tying it higher at a height that is proportional to the separation between the trees with some initial sag in the hammock suspension lines.
Often, it is the method of not tying the hammock initially high enough and putting some slack in the hammock suspension lines that contributes to the ridgeline failure. Tying the hammock lower, pulling the suspension lines taut and retightening as necessary to raise the hammock to the height you desire is putting more force on your hammock's suspension system. There are a few posts about that in this thread
describing the additional forces created when you do that.