The point of them belittling you is to get a reaction. Do not react; be proactive. Write out your situations and what they had said to you and what you had done back. When they say something that isn't true let them know you disagree. When she says that what you had said was pointless then ask her: "What is your evidence that what I had said was stupid?" Another thing you could say so they will stop with their manipulative belittling behavior is : "It's a common opinion that co-workers think that other co-workers are stupid, though I wasn't expecting it coming from you." Or "I read in a business magazine where co-workers like to think that other co-workers don't do their job well." There is also a fogging technique you can use, when something they say is true with an attitude. say back calmly: Yes, I agree that ...... If it is somewhat true, agree on the part that is true and tell them you disagree on the other part. You can even ask why they said what isn't true from their perspective. And if it is completely untrue say something like: "Yeah someone in another universe may possibly believe that." Say all these back emotionless and calmly but firm. They want that reaction because that's what makes them feel good. They want to see you hurt. If they continue after doing these attempts a couple times; confronting them about how you feel is the next step. Saying something like calmly: "When you girls make fun of me, I feel insulted and don't appreciate it. I want it to stop." And continue to repeat back how you feel and how you don't like it that is if they don't agree and continue to try to manipulate you and take you off topic. Use the broken record technique. You can reduce your sentence down to "I want it to stop" then as you keep repeating and rephrasing back. Another one I think is that you can eventually ask them "Do you like it when others pick on you?" And tell them that you don't know of anyone who likes it.

If you would keep this up if they are still there and haven't been fired they soon may give you respect back. If not, then ignoring them may do the trick and do your own work. Don't take what they say personally unless it is something true that you can fix. Be happy, honest and calm.

I would look up assertiveness too. I have taken a course on it and also have a book. Assertive is the most confident personality and it isn't bossy though you are standing up for yourself the right way. These techniques I've learned from reading about it. You are direct, honest and positive. You kill anger and negativity with kindness.