Cheating a cheating player back leads to more cheating and hurts your reputation.
When I talk with players, parents and coaches the topic of cheating will often come up. There is concern with how to deal with cheating. When I ask the audience what they should do many will say to "cheat them back". I understand the frustration and wanting to get back at the person cheating. However, cheating someone that is cheating does not work!
Cheating a "cheater" (I use this term lightly and because this is how players refer to people that cheat) is not an effective strategy. Why? You are now distracted and focused more on getting back at your opponent than playing your game. Furthermore, you are playing the "cheaters" game. They want this drama because they feel it will help them win. And, do you think cheating them will make them stop? No. It will only motivate them to cheat you again because how dare you cheat them. What ensues is a battle to get back at the opponent with worse and worse cheating and behavior.
While the match it's self will become a disaster because neither player is focused on tennis, the long term damage is what coaches, players, and parents say about you. Your reputation will be affected by cheating the "cheater". You will know begin to be known as the "cheater". Do you want that title? I wouldn't.
Even worse that being called a "cheater" is that the word can spread to other players. Once you are known as a "cheater" other players will come out to matches sensitive to your calls and potentially be ready to cheat you first (or at least question any of your close calls). Now what was a one-time issue with a certain opponent has become a reoccurring nightmare of being questioned, and even questioning yourself about your line calls.
Do not fall in to the trap of cheating the "cheater". Not only will it hurt your performance in the match you are playing but long term it can negatively affect your reputation. And it is a lot harder to change a "cheater" reputation than it is to get it in the first place.