How do I stop myself from being an asshole?

This vague question probably needs explaining.

I have always been prone to jumping to conclusions, saying things without thinking through the social ramifications, and generally making a fool of myself. Often, when I'm talking to people who contradict my world views in a serious way (eg: if they don't believe in evolution, or think that torture is warranted) I literally rage to the point where I can no longer make intelligible conversation. In stressful social situations, I literally have panic attacks. This is a big problem, since I am going into a career which will require that I talk with people, many of whom will disagree with me, on a regular basis.

I've always been quite the introvert, as well. All told, I would not give myself very good scores on the social graces meter.

But before I start thinking seriously about talking to a professional (I am worried that they will just give me some pills and call it a day), I am wondering if there are others on reddit who have dealt with such problems, and if there are any good methods for being more considerate and dealing better with social stress that do not involve sucking back psychoactive drugs on a daily basis.

I hope that merely acknowledging my character flaws is a good start. Even if I get few or no responses, I think this was a good idea.

Thank you in advance for any advice you might have!

PS: Because of my schedule of coursework, I will not be able to respond to all posts, and can only log in to reddit occasionally.