What would be an appropriate response for accusation?

Recently one opponent accused me of using engine and said they are going to report me. 

What would be an appropriate response? And should I report them back? 

PS. I have never used engine nor AI. 

Find it in your heart to forgive. Release yourself from wanting revenge, see yourself for the love you intrinsically are. Life is too short.

I would be proud

I usually respond with " Luke, I AM your Father!" Other times, I simply say "What gave me away?"

I had gone 17 wins, 1 draw and no losses when an opponent asked me if I was cheating. I said report me if you think I have or will in our game. I don'

I was taking my sweet time on my moves, as usual, and one guy chatted to me "stop cheating", I responded "I'll take that as a compliment". Fair enough he said. After I won I had an accuracy of about 55% and let him know, that was that. There's no point in reporting someone for accusing you imo, just take comfort in that you were making him uncomfortable.

I've seen you tubers reporting people for cheating. One of the criteria was that they had an accuracy of 97%. I beat someone at the weekend with 97% with only one inaccuracy in a game with over 55 moves. I've had 99 a couple of times, probably shorter games.

You could eaasliy turn off chat and I guarantee the issue will never come up again. Or leave it on and take your chances.

You could report them for that but if you're playing fairly you have nothing to worry about

https://support.chess.com/en/articles/8598004-they-reported-me-for-cheating-but-i-didn-t-cheat-am-i-in-trouble

An appropriate response would be SHAW! ADINO! GIT GUD!