What's the word or phrase when one takes advantage of you but pretends and mocks you for thinking that way
Solution 1:
This should be what you are looking for -
Gaslight
verb
gerund or present participle: gaslighting: manipulate (someone) by psychological means into doubting their own sanity.
(From Lexico)
Edit
I just realized this got mentioned in the comments. So I'll give credit to StoneyB.