Listen to me before its too late! D-I-V-O-R-C-E!
I am a Psychologist and I have lived Aikido since 1989. This is not a problem with you nor of your student. even if you kick your student out or quit aikido altogether, it will not solve your problem. Your wife will simply find another object of her jealousy.
This is not about lacking trust or being suspicious anymore. This is about psychological control. Just as rapists aren't motivated by just the need for sex but by the need for power, women like that are using jealousy as an excuse to assert their absolute control over you. I betcha she also uses maneuvers to make you feel guilty or to make herself look pitiful in order to sway not just your actions but also the opinions of people around you.
Don't try to be a miracle worker. She is not going to change anytime soon. They never do. I say no more of this marriage counseling BS. Bail out now! Don't wait for a fight or an excuse to explain your decision, just cut her loose ASAP. And that means NOW.
A divorce has best chances of being more civil when it is not precipitated by a fight. If kids are involved, try to agree on custody and visitation but bottom line is, you need to do this now.
I am also a licensed psychologist and Aikido instructor who is appalled by your comments. I strongly suggest that you review APA ethics guidelines. You should simply state things as your personal opinion, rather than an implied professional opinion regarding someone you have never met, treated, or evaluated before. My personal opinion is that you have made an a lot of opinions and recommendations based upon scant information. I could go on further, but my parents told me to say nothing at all, rather than some unkind words...