How do you combat gas lighting?

I am trying to remind myself of facts which are real, but I'm still struggling. I'm trying to resist the urge to just go along with the gas lighters (false) version of events in order to make nice, but it's hard. I just want these negative feelings to go away. I know that giving in would stop the conflict for now but would be a bad idea in the long run. (A very bad idea!)

I just have a horrible internal struggle right now and don't want to feel this way….

How do you combat gas lighting?