don't worry

You have right to be upset.   Also, you have told them it was not because of them, so you didn't really blame them of anything.   It is not good to cry, but it is also not terrible.
I feel for you, but I won't cry anymore, I figured that out in college.  :)   they are not obliged to invite you.  All you can do is to be a good employee and a good friend.   And you will get what you deserve.  Try to be a fun person, so people will be atracted to you.  If not, be a helpful person.  If not that, be yourself and be happy with yourself.