I feel Very much the same way quite often, unimportant, broken, used, forgotten, not the top priority in anyone's life, nothing's going well, or good for that matter, no one to turn to, no friends, unloved, unattractive, unhealthy, unwanted, so on, so forth.
I also find I feel this mostly at night... Moreso when I'm alone and actually get time to think... I don't think others necessarily cause me to feel this way, as if they do or say something to cause it, but I do think a lack of connection with others causes it, a lack of desire from others to have me in their life. Just... A lack of friends, a lack of relationships, and heartbreak lol.
I do think I have little to no luck in life. lol I know they say you have to make your own luck, but I'll be damned if I know how. I especially know I don't seem to have any luck with women lol I'm lucky if I can even get one to have a conversation with me if she isn't a co-worker or whatever.
I figure things can only get better when I can't imagine them being worse, and I've been to that point - I was last Saturday (the 6th), when everything culminated and my ex decided it was a great time to split. Since then I may have found someone else that something may work out with, but I have so little confidence given the way things have gone in the past that I couldn't tell you whether I've got a shot with her at all, or if we'll even remain friends after she leaves in a week or two.
Not knowing, is the biggest fear I have in life... The "why" questions are what kill me.