Why do I start getting sad when I look at facebook pictures?

[Glitter Lady ♥]

Why do I get sad and cry a little when I see pictures of my friends and their families? Friends that I have known since hildhood and we have grown apart, but still deep in my heart I feel bad for not keeping contact, and seeing them on pictures in facebook, all happy with their families juat makes me sad. I realize how different I have become, I've gotten colder, and I am not nearly as friendly nor warm anymore.... I see the in person and I don't talk to them... I don't know why.

I think that I am just a mean person now. Ever since I moved I have gotten used to being alone.. No father, no best friend, no bf, no one.

Grew up poor, and only relied on school to get me out of being poor.

I don't know why I am so cold, like I just don't care about anything, and I feel lonely, empty, and scared of these feelings sometimes..

I miss my best friend, my bf, my dad, but they all went away... now I am sad.

How can I let go, be happy, still be warm hearted, nice, strong, and satisfied with my life?
How can I learn to see the beauty of it?
I have also been diagnosed with a chronic disease and that depresses me a little it makes me stressed, worried, and I think too much, but I can manage it with the help of the professionals... I hate diabetes, but I guess it's managable..

What I'm trying to say is, how to stop being sad? I know I feel sad, and I feel ashamed if I ever showed anyone that I am but it makes me feel alive a little when I still feel sad. But I never felt as sad as I do ever since I lost my dad, best friend and boyfriend.. I kind of feel like I am a failure. I wish I could have been a better person, if I was then I would still have them all in my life somehow I don't and life sucks a little without them. But I have to accept?