M.,
If the coach is truly verbally abusive and your son is going to be miserable the whole season, you need to either put your child on another team or quit T-ball. There are lots of other opportunities out there and no one will have a ruined childhood because they missed a year of T-ball. Maybe your child would like to try something different anyway.
If your son really wants to play, there are no other teams available and the coach is more obnoxious than abusive you need to let it go. Children are very resilient and you need to step back and look at whether this is really traumatizing him or just you.
My children have been exposed to many adults in their lives who are "less than best examples" and if I could have chosen someone else to be in their place, I certainly would have. But it gave us the opportunity to talk about doing what is right even when the adults around us don't and not to let other people's comments govern how we view ourselves. (Essential qualities found less and less in people today.)
If the coach is just too intense, (and don't think I am excusing the behavior because I am not,) your reaction to her, the way you talk about her to others and interact with her will carry a greater impact on your son than the coach's behavior. So this probably won't be the coach that your son remembers fondly for the years to come. This will be the coach that tests, tries and refines the character of you and your son.
Best of luck,
S.