Disappointed and Let Down

People are not perfect. I don't expect them to be. I'm not perfect and will daily do or say something that I later regret. The hope we have is that we have a forgiving God who daily gives us grace and mercy.
Also, people will let us down. They will hurt us whether intentionally or unintentionally. It is a part of life and it is to be expected. However, knowing that fact doesn't mean it hurts any less.
I fear being hurt. It's hard for me to let people get close to me. It's like I keep this invisible wall around me. In the past, I've kept it pretty thick in order to protect myself.
Over the last few years, the wall has become less thick and possibly not so high. I've let a few more people break through it. The last few weeks I've been asking myself if this was a wise thing for me to do. It seems that when a person is close to you, that person will learn your fears and weaknesses and that is where they will attack you.
I've been going through this over the last couple of months with a friend that I consider to be a brother. Things have totally switched. On most days I have no idea what is going on or where we stand. When we talk, he won't tell me his heart, only attacks me. I don't want to attack back so I've just been keeping quiet. I try to also pretend things are fine and treat him no differently than before, but it's hard. Most days I just want to keep a distance. I want things to remain like they used to be. But, then I think maybe his season for being a strong influence in my life is coming to an end.
But, now it's causing my heart to sin. When I'm around him, I feel angry and bitter. I feel annoyed. I feel rejected, disappointed and let down.
I've discovered that the walls are going back up. They are again climbing higher and thickening. Something in my mind keeps telling me over and over: don't trust anyone, protect yourself, you never should have let anyone that close, etc.
I don't want to go backwards. Since the walls are going back up, that means I'm starting to distance myself from the women here that I love deeply. My relationship with many of them transcends ministry. They have been my sisters, aunts, mothers, and grandmothers. They've been the ones to teach me how to live in Uganda. They've been there. I want to continue to love them without fear. But, the fear is there.
Right now, my heart feels vulnerable, like it needs to be protected. I don't like feeling vulnerable. I don't want to be hurt. But, I also don't want to be isolated and lonely. I want to find that balance of loving like I've never been hurt while at the same time not putting myself in a position to be hurt.