Bad Friend/Bad Person

I have been feeling lately that I am a bad friend.  I think I have chose a few wrong ones, but I know that I have also chose a few right ones.  I have a ton of guilt and shame because I can't or don't keep plans because people just don't seem to understand or get me. (Totally not why I don't keep the plans)  I wish these people, hell I wish everyone really understood depression.   I wish they understood it like I was living it.  I am trying really hard here NOT to use it as my crutch, but frankly, it's the only exuse for my actions and the reason I have changed from that old bubbly cheerful Melanie to what I am now.  And I don't even know how to describe what I am now.  I have been getting and hearing some of why don't I hear from you anymore?  Why this, why that?  I try to explain it, but I sound and feel like a broken record.  I feel like no one understands unless they go thru what I do.  And they do.  There are more people than I thought know so much and understand.  I was shocked when I joined some Bi polar 2 groups on Facebook.  Maybe they are my people.  Maybe I should start trying to become friends with them and be more active in those groups.  I am trying to be positive though and I hate to say this, but they all seem soooooooooo low.  Lower than me if that is even possible.   And well I guess it is.  My throat is closing up some and I am getting teary eyed writing this because I really really miss who i used to be.  I try so hard, but I can't please everyone.  Not even myself.