He cut me off, now wants to return...

My friends and I have been close for years, but one of them cut me off a while ago after we had a fight. This hurt me a lot and I was upset for months, which made sense because I have always looked at them as a kind of support system. My family isn’t close to me, so my friends have always played a more significant role in my life than anyone else. I was depressed and angry, but after a while I decided to put that behind me and move on. He got in touch a few days ago and asked if I would consider letting him back into my life. I haven’t responded yet because I honestly don’t know what to say. On the one hand, it would be great to be friends again, but I am also nervous because if he goes away after another disagreement, I can’t imagine putting myself through that pain all over again. What should I do?
You should understand that all relationships evolve through learning, which sometimes leads to pain. It is through that pain that you can emerge with something valuable, as well as the insight that every relationship can end. You can’t choose to be with people only because you assume they will always be part of your life. You can’t hold on to everyone either because you may one day decide to cut ties with someone too. All that matters is whether this friend is important to you, and if you believe your life is better with him in it. Everything else is about being open and understanding, and working towards building a better, stronger friendship.

I don’t know if my girlfriend is using her friends to manipulate me in some way, but I suspect it is happening and I am always angry around her these days. How do I control this situation?
Why absolve yourself from making decisions about your life, and assume your girlfriend or her friends have an outsized influence on what you do?