Hi DaX

First of all I don't see you as worthless at all!!
But I am really sorry that you feel that some people in your life don't appreciate you.......they should!!!

As for feeling so hurt when people you trust let you down, I think that's very understandable, after all you have made an emotional investment in them and in trusting they won't let you down.......other people you don't have that trust with.......well not such an emotional investment..........so it's not you at fault there it's those who've let you down
As for the people you trust letting you down though perhaps you could re-evaluate the level of trust or the expectations you have in them.........e.g. you might be able to trust them 100% in some areas, but in others they may be real falible and risk letting you down...........so maybe adjust your expectations in those areas???

The lows and highs though...........the lows..........I know your life circumstances, the people around you and depression have a big impact on those ...........but the highs..........are there any..........even vague..........triggers you can think of which may cause them (assuming they aren't dangerous highs!!).............maybe something has given you a little hope, maybe something has helped shift your perspective on your situation or your future, maybe you've felt a sense of some achievment, maybe something has made you feel a little better about yourself, maybe you've felt a sense of connection, maybe any or all of the above........because those things/thoughts/feelings are really worth trying to hold onto as much/long as you can, maybe evne write those things down to remind yourself when things are starting to look "bad"??
So yes, I don't think that the sudden high's are necessarily a bad thing...........depending..........because sometimes some spark/some bright light/some break in the clouds of depression/some actual hope when you've had so little can feel so good.
For some people without depression the circumstances causing them/the feelings may be "no big deal", but when you're really struggling and..........well that can be different.............
So..........if you think...........try to hold onto them???

Something to change..........maybe try setting yourself some real small goals to start with...........and they could be anything at all............not forgetting to give yourself real positive praise for achieving them either!!!!

But.........finally..........DaX, while you're on here, you're not alone

Alison