This is probably not the advice you were seeking but, since you were bullied, I'm going to go ahead and give you the advise you didn't really ask for. If you don't have a therapist, I recommend you get one. If you do, it would benefit you greatly to discuss this issue with them. They can help you sort through your feelings about what happened and give you tools to overcome your hesitancy to trust people, including learning how to set boundaries so you don't get bullied again. With greater clarity and understanding, you can work on building new friendships/relationships.