ego !What does it mean? When we use it?

Feelings! I've been have weird feeling, I've ever felt it.. I've felt some of my close "friends and family members" they became like strangers , I don't feel comfortable to talk with them in anything like we used to do :( .. I wonder what's the problem. Right many of my thought are changed, but does it that affect on my relationships!!

لا إلــه الاّ أنـــت ، سبحانكَ إنّــي كُنت من الظّالمين

عنــدما تضيقُ بي الدّنيــا لا أجــد سوى هذه الكلمة على لِســاني.