Am in a hard time in my life,having trouble with fitting in what do I?

Well am 20 and my dad latley been talking to me about stuff I have no control over ,well my friends dumped me ,my best friend like a brother to me has now left me because he just moved on I know its not his fault ,but the other cool guys Ive been hangin out with don't even bother with me because they found out am not the "cool" guy and they are just in it for the girls and am the type of guy that is kind of shy but at the same time just a ok guy that doesnt say much,now am left with my self and my Dad is starting to notice that I have no friends and says hey why don't you go hang out with your friend across the street but the thing is that guy is just at a point were he hates people like me he's more of the popular type with 3 girlfriends and has everything and am just more the introvert,now I find my self in a position I havn't been in since 6th grade,and am 20 and I fill that my only way out is to follow my dreams and to join the military but my family will be against that I fill so stuck what do I tell my Dad?.