Your opponent didn't do anything. You just lost your connection.
It happens.
I don't think that support will give you any points back.
There are tips to help you maintain your connection.
https://support.chess.com/article/213-how-do-i-fix-my-disconnect-lag-issues
So the player in question is:
https://www.chess.com/member/dmh327
You can find our game, I had a clear lead by time he went AFK (I'm white in this position).
It's a shame that people go AFK and stall matches when they're losing, and it usually ends with you winning on time anyway. However, in the case you end up disconnecting while they are letting the time run, it results in a loss for you and a win for the abuser.
I sat for approximately 5 - 7 minutes before I had to get up and use the restroom, and when I got back a minute later it said I disconnected (I WAS AFK FOR 1 AND A HALF MINUTES AND I GET DISCONNECTED, WHAT?!) and I was abducted 8 or 9 points off my rating. While my rating isn't exactly the best, it doesn't change the fact that I've been trying to get better and reach my goal of 1,000 in rapid (I started at 800, went down to 500, and back again).
I filed a report, I don't know if the support team will actually adjust ratings or omit games due to this behavior. I'm just speaking out about how unfair this is.