Interesting topic. Something which most of us have experienced in life.
Like you said, it's all about matter of perspective. Each of us will look and take things in our own ways.
In my opinion, there is always ups and downs in friendships. We tend to have those little fights with our friends but then we mend and get back together.
But as for those who back-stab/backbite/hurt us in the worst possible way - they are
not even our friends.
"If a friend envies you, then he is not a true friend." - Imam Ali (AS)Life is a lesson. We learn from it - from the good and from the bad that afflicts us. As a human being, I don't like to keep grudges. I tend to forgive and forget, but that's just me - I know many who wouldn't agree. Life is a merely a lesson, we learn from our mistakes. It makes us more wise and mature in terms of knowing who's your friend and who's not. The hardships and difficulties of life had made me stronger and move on rather than put me down because I know for a fact that people come and go but my Lord is always with me. He is there for me when no one else is. And, for me ... my Lord is enough -this is how I look at it.
"Verily with hardship comes ease." - (Quran 94:6)"And grieve not over them, and be not distressed because of what they plot." - (Quran 16:127)PS- what goes around comes back around.