Down

Been trying to stay off here.  It is that time of year again when all the kids go off to college and the empty nest board gains members.  At first when I joined it helped to have others struggling like I was struggling, but I have watched them all go one by one.   They improve as the year goes by and although the holidays are hard once we get into January they get busy with their lives and move forward.
I on the other hand after two years and not better at all.   I am still begging for attention from my children and crying like a 2 year old when I don't get it.   I hurt all the time over their neglect and just can't accept that they are grown, gone and don't think about me.   Unanswered questions, unaccepted invitations, trying politely to back our of family traditions....They don't really want to hurt me they just want to move on with their lives.
But I have no life without them.   They were my world for too many years and there is nothing left.  I know I need to let them go, but then I will be all alone.   I put too much pressure on my middle son, the one that does come to see me, yesterday when he tried to back out of an outing on Saturday.   He said he was tired and wanted to sleep, then admitted he would be getting up to go to his wife's brother's football games.  I guilted him.   I told myself to shut up.  I told myself not to do it.  And then I told him he was making me sad.   Now he is going again and I feel horrible.  I am not going to enjoy Saturday.  I will be looking at him the whole time and knowing I made him go.
Then feeling bad I sent him an apology this morning.   He did not reply to me for 8 hours .  I sent another msg with times and he msged back, but when he did he sounded snippish, saying he told me three times he would go.  Also sent a msg to my oldest saying I would not be home tonight, but would be next Thursday if he was coming by and that I missed him.   He still hasn't replied, but no surprise as he didn't answer my questions from yesterday.
I am such a mess.  Youngest son hurt his back this week and has been very grumpy.  Got upset at something I was asked to do at work that violated ethics to me and started looking at others jobs.  Just added to my depression.  Haven't seen my one friend in 3 weeks.  I have been working Friday mornings and asked if we could move our day.   She didn't even answer me.  Have asked last week and this week and she hasn't answered either.  
I had been stable for over a month now and feel like I have hit bottom again.  Been in tears 3 times so far in 24 hours.   Don't know where to go from here.