While you are looking for that new job, which seems your only real choice, it is CYA time.
While rational discussion is good, keep in mind your dealing with a crazy person and a person married to one. I think it would be prudent to do a little home work before having this frank, polite, professional, rational discussion, because if you are like most of us that work, losing a job is inconvenient, and within a month or two or three it could be a disaster.
Even if your boss is receptive, his wife probably will not be, and being Ohio has provisions for the division of marital property, chances are his losing her carries more economic weight, than his losing you, let alone the issues of consortium that are involved.
Furthermore, most states are employment at will, thus an employer is not obligated to give you a raise, or even a reason for discharge, unless a contract or employment agreement has been executed. As you are part of a franchise system, there maybe an employee hand book for use by franchisees, and even though it will generally contain a disclaimer, regarding the construing of it as a contract of employment, I have seen several occasions were it was in fact held by courts in Kansas, Missouri, Oklahoma, and Colorado to be in fact a contract of employment.
The CYA part
Keep a contemporaneous log, noting times and dates along with details of the incidents, also note names of witnesses.
I you have a small recorder carry it with you, and try to record her tirades, if possible use it to tape her calls to you, and record their times.
Keep copies of all memos, e-mails, and other correspondence, etc.
Try to get a copy of his franchise agreement, these often will define expected human resource issues, if he is operating in violation of the policies and procedures within the agreement, it could place his franchise at risk thus somewhat off setting his wifes economic weight.
Educate your self, while it may be employment at will, this is not carte blanche, not only are there federal exception under EEOC, ADA, and other, but many states as well as local governments have expanded provisions. If you were to be discriminated against by violation of these statutes, the settlement options can be quite lucrative. Frequently part of franchising fee includes insurance coverage, and often, when confronted by an employee complaint to an agency like the EEOC or the Labor Department, insurance carriers find it less expensive to offer settlement than to contest allegations, thus softening the economic impact while you seek other employment.
The good news is with your experience in restaurant management, and the expansion of the service industry sector, you should be highly desirable and readily employable by many fast food operations, which have decent benefits, and entry-level management usually starts in the high 20s to low 30s. Also management experience in and of it self is desirable even in dissimilar settings.
As to continuing education, many state university systems offer degree completion through the junior college system, and internet, while the variety of degrees is limited, it does not matter, I know few people that actually work in their major.
In any event I wish you well, and remember life is to short to do something you hate for to long.
Life is no joke but funny things happen
jon