my friend always makes jokes about me being stupid and its starting to annoy me? Am I just taking it too seriously because I do know myself too overreact at times.

It depends how your friend is joking about you either by kidding and just making a laugh about it and move on or they are teasing and taunting you which is more serious than them being funny and silly.

I don't think it's an overreaction. Your feelings are valid and you shouldn't have to be put up with being picked by the people you call your friends.

Pull them aside and talk about how it makes you feel. Communication is key to any relationship. You are not taking anything too seriously, if it hurts you it hurts you. It is as simple as that. Try to talk to them. Tell them about how these jokes make you feel and how hurtful they are. Maybe even set a gentle boundary against these jokes. Let them know how you feel. You are not overacting at all. All of these emotions are completely valid in this situation and the best thing to do is clearly communicating your feelings to them.