Unfortunately, Julia, there's not a great way to effectively respond to a gaslighter. They don't usually listen to reason.

If you are persistent, you might get him or her to go to therapy, where a third party can point out the lies and inconsistencies. But the best thing you can do is get a support system for yourself, get a reminder that you are really not losing your mind, you are not at fault, you're not to blame. If the things in this essay are often said to you, then you are definitely being emotionally battered and mistreated.

I'm more than willing to discuss with you if you'd like.