Do anti-depressants work and are they addictive?

Ive been very unhappy for the last few years. Im single, balding, fat and live at home with my parents, im 28! I have no money and keep losing jobs. I smoked weed everyday for 7 years but quit it 6 months ago as i was getting very paranoid! Ive never had a relationship which makes me sad, a girl i was close friends with broke my heart once at 21 and i stopped caring about things. Recently ive been drinking more than ever and last week was so drunk in cant remember anything, my friend said i was trying to fight everyone and urinated against the bar got thrown out by the bouncers and tryed to fight them, i dont remember a thing! Im becoming the very thing i hate. Why do i get like this i want to be optimistic, i have quite a bit going for me why do i feel so sad? I have heard that the excesssive weed smoking can stop the release of the feel-good chemical in your brain? If the anti-depressants help the imbalance would that continue when stopped?