when someone 'insinuates' something false at you online or in real life, how should you respond

Most of the time it's worth ignoring.
Folk who say stuff like that are just trying to bait you into argument.

If they do it in person challenge them as to what they mean by it.

Make a mental note of it, wait for the opportunity, fuck up their life.

Most times they tell me then block me cause I'm not gonna argue and they know I'd lock them. They like saying shit and block cause they think it's funny