My penis is 5.5 inches and my girfriend broke up with me for being small. How can I get over it?

We were together for 8 months and as soon as she saw it she said 'Damn I thought you were a man where is the rest of your manhood at." She then wrote on facebook small penis jokes like I think i have an asian boyfriend he's smart but not packing. How can I get over her I am thinking of breaking up but idk if i will find another girl if she keeps getting word out i am small.