Well you should tell her how you felt when she laughed at you that’s the first thing you should do and have a open conversation on how you feel about your insecurities

Hey! Thank you for reaching out. I understand its actually very difficult to cope with something being pointed out when we are very insecure about it. But when people make fun of other’s it actually is their defense mechanism they project their insecurities on to others. Self love is a long road but what you can do right now is. Be confident in your own skin. Confront your friend and politely tell her that this has been bothering you and it will be better if she doesn’t talk about your insecurities. Friends are supposed to give a safe space. Friends should also respect each other.