What do you call someone who constantly criticizes?

Probably a “hypercritic” – a person who is excessively or captiously critical. Or “hypercritical” as an adjective. You could concatenate “constantly ratifying”, “self-righteous” and “hypercritic” to call such a person a “constantly ratifying self-righteous hypercritic”.

What do you call a person who finds fault with everything?

A name for one who finds problems in everything, no matter how small, is a nitpicker. A nitpicker is a person who finds faults, however small or unimportant, everywhere they look.

What to do when someone is constantly putting you down?

How To Deal With People Who Put You DownRealize that their comments reflect on them, NOT you. Consider the counter-evidence. Put things firmly in perspective. Ask whether there was anything constructive in the put down. Don’t attack them in return. Laugh it off. Say thank you. Tell them how it makes you feel.

What is belittling behavior?

The definition of “belittle” can be easily surmised from the two words that it is made up of, “be” and “little.” Said another way, belittling is language or behavior that literally makes someone feel small, unimportant, inferior or minimized.