Second guy was still in high school. Insanity plea or not, he was still a minor and you get a clean slate once you're an adult.It's in his book. He stabbed somebody with a knife, but the knife hit the guy's belt and didn't actually hurt him.
Other guy was charged and blamed it on stress because he really wanted to be a doctor and had a good lawyer, which is what OP needs.
As for Ben Carson, he also may have been a juvenile at the time. The key word is still almost. He didn't end up stabbing anyone.
The issue for the OP is that he is a sane and rational adult who has had some opportunities in life...and he still committed a violent crime. Essentially, he could be a major risk for a school his episode turns out not to be an isolated incident. The conviction is a big deal.