By convincing yourself that u hate the boy u will be once again fooling urself like u are doing at the moment by those unreasonable thoughts thats making u depressed. Just focus on those thoughts that made u break up with ur bf. Just continue being freinds with him. Dont be jealous about his social life remember everybody has different goals and purposes in life. No situation or anything can make one happy more than their own thought process. So its not the break up or his active social life or ur dull life thats eating urself up from inside but its ur own unreasonable interpretations about it thats making u go nuts.