After 50 moves with no captures or pawn moves, it's supposed to be an automatic draw.
Opposite colored bishop: whoever has more time wins?
"Unsportive" behaviour is a part of (especially) online blitz chess. As is premove.
As you improve you simply learn to accept it as part of the game. And perhaps use it to your own advantage?
If you played a good game up to that point, then good. You've played good chess. Who cares if he desperately wanted the win by timepush and by giving himself a heartattack. Move on, play another game. Not the end of the world.
For every jerk there's usually a sportive friendly chess player online as well.
I'm rather annoyed. I just played a game (not on chess.com) where it was very clearly a drawn position. Very clearly. Neither of us could move any pawns and it was opposite colored bishops.
However, my opponent had more time than me. It wasn't like I was almost out of time, I still had a couple of minutes. At first, I couldn't understand why he wouldn't accept the draw.
But he just kept making filler moves. I went through 40-50 moves like this, just moving bishops around and me trying (in vain) to land a threefold repitition. He would move his bishop one space, then just walk his king around the board and do it again. Is this...is there no rule against this in chess? I think there should be...I feel sort of cheated. It was the lamest way to lose I've ever experienced.