I'm sorry. Relationships can be terribly hard. My sister has recently hurt me very badly, to the point that I can no longer think of her as a friend. I have been finding helpful quotes and writing them on notecards lately, although usually I forget to look at them! But one of them is, "the truth is, everyone is going to hurt you. You just have to find the ones worth suffering for." Sometimes, that may be only 2 people, or maybe only one, but just having one person who means that to you, can make a world of difference. Sometimes having a pet can be the relationship that makes a world of difference.
Could you look at isolation as a more temporary experience? Like, right now it sounds like it is really really hard for you to trust people, but then something might happen next week or next month, and you might change your mind and feel more hopeful.