Can you guys help me?

There is guy that likes me but I don't know how to respond to him. I don't have romantic feelings for him yet but he has all the things that I'm looking for in a guy and we get along really well.
I don't know how to react when he tries to flirt with me or compliments me so I always act in a dumb way or just try to change the subject.
I feel like he is starting to think that I'm weird when I just have really low self-esteem, low self-confidence and I'm socially awkward.
It's really hard for me to open up to someone because I was bullied in elementary school and in high school and I was also sexsually harrassed by one of my classmates from the age of 8 until the age of 10. He moved away and I never seen him since then but I can't tell anyone what happened because they wouldn't believe me.
I'm really confused right now. I don't know what to do. I'm afraid to talk to him about my problems because there was a few people in the past that just laughed at me and said that I don't have problems I'm just weak so I just stopped talking about myself because they don't believe me and they look down on me. I'm afraid that he is going to hate me if I countinue to avoid him like this and I don't want that.