Why does my life surround around the fact that i am fat?

i know that sound like a weird question to most normal people. i have just come to realize that my entire life surrounds around the fact that i am fat. i do not hang out with old friends, go to social events, or even just go out alone cuz of embarrment of how i look. i never talk to guys and feel like no guys would ever take interest in me. at this point, i think its crazy that i let myself get like this. i have so much other stuff going on my life that is more imp. ex, i am very school oriented and working hard to get where i want to be in life. so why am i so obsessed with the fact that i am fat. why am i so embarred? any insight would be greatly apprecited. this question is not about how to lost weight, i just want to understand how i mentally go this why, and why i do this to myself? thanksss!