My ex left without fully explaining but I feel broken and empty

About 5 months ago my ex left without fully explaining why. For me it seemed out of the blue. I don't miss her as much as I used to but I just don't trust people anymore, not even my friends who I have known since my childhood not even my family. I'm so terrified of being judged or dismissed. Instead of acting like someone else or putting on a mask of a personality, I've just shut down. I haven't felt that sense of comfort and happiness with myself since everything fell apart. I'm scared to because I don't want it to be taken away from me again. I feel like ever lesson I learn only last a day. I just don't know what to do. I'm working at a place I know I should enjoy. I'm keeping up with my creative passions: working out, eating healthy, etc. I'm doing everything the books say I should do, but I don't feel any different. I just don't know what to do.