I wish I had advice on how to raise someone up and make them a better person. In some cases, it helps to remind people that you aren't their punching bag and that they need to either learn to treat you better or get out of your way.

offthepoint's advice is good, and that's the first thing you should try. It's mature and clear.

As for Having quick retorts? It is tough. For some people its reflexive, for others not so much. Part of it is related to how experienced you are at standing up for yourself and how much time you are willing to spend understanding the buttons of the people around you.

A lot of the advice is simply "stand up for yourself". I've found that harder in certain situations, for example: family, when you don't want to completely obliterate the relationship or there are other relational effects.

Sometimes it helps to go over a list of incidents so that you are quicker to respond and able to call someone out for a pattern of bad behavior. (It also stops you from getting into old comfortable habits when you deal with a person