Help...i have no friends

Who else finds it impossible to maintain relationships?? I try so so hard with people, i just must be lacking somehow because people just do not like me. For example:
# I work with a heap of women who have kids my kids age. We webt to uni together and used to hang out. They regularly catch up. I used to be invited but its been over a year since an invite. When i invite them no one replies or shows up. Im facebook friends with them so see all their gatherings online.
# My sister who i never see is holidaying 1 hour from my house.....no work on catching up.
# my mothers groip ignored me till i left.
# My best friend is having a party tonight that i am not invited to.....she is everything to me and im obviously nothing to her.
# my other "friend" is never avail because her kid is always "napping" if he is tryly nappung as much as she says she needs to go to a dr stat.
# i frequently find out im not friends with people when i am deleted off facebook. This has happened quite a few times.
Damn facebook makes you realise how messed up your life really is.
I have depression but i dont post rmo stuff online i rarely post anything because i figure no one cares about my life anyway.
Anyway i am lonely.
The end.