My question is, does this kind of verbal and sometimes physical abuse lead to any character building? If I decide to stay with my current Sensei, is there any chance I can become a better individual or will it destroy me? I've read that students often become like their teachers. I don't want to have the same personality as my Sensei, but I do love his technique... On the other hand, I would love to improve my own personality, but I don't know if standing verbal abuse will help me achieve that goal or not.
Anything can be character building. The question is how it's affecting you. If you're feeling worthless, it doesn't seem to be working too well. In jobs like the military where the needs of the many significantly outweigh the needs of the individual it makes more sense. In a martial arts dojo I don't think it does so much. You can "improve" your personality by being a sincere person who employs self-reflection and any number of other self-affirming activities.
That said, some people are more sarcastic than others. People are sometimes shocked with how me and my friends talk to each other, but we know where we're coming from. It's hard to judge from a distance.
Whatever the case, know your self-worth comes from within and has nothing to do with what other people think of you. Take what others say as food for thought. Maybe even thank them for offering their opinions, but always think for yourself and be your own person.
...or don't. Who am I to tell you what to think?