Hey Liz, maybe you should work the other direction,
and see if you can't find someone who specializes in exams / exam anxiety.
Lots of people have this issue.
They have specialized training for many exams, and you might be able
to work with someone who can help you with "strategy and confidence"
which sounds like the real issue--not knowledge.
I teach in a university, and I've seen many students who have this exact problem.
It is possible to overcome--sending you a hug
P.S.
Your ex is still an asshat.
Put his and his issues on the back burner as much as you can and let the court sort it out.