On the issue of his wife filing for divorce, I'm actually primarily a divorce lawyer in Tennessee (obviously neither he nor his wife is my client). There is a mandatory waiting period after filing before you can get divorced. If you have minor children together, it's 90 days; if you don't, it's 60 days.
The hurdle for her is going to be service of process. She will have to get him served to divorce him. She could, I suppose, serve him by publication in the newspaper, but if she does, then the court won't have jurisdiction to assess alimony and divide marital property. Given that probably everything she owns is marital property due to the length of the marriage, she wouldn't be able to get clear title to a house or property without actual, rather than constructive, service. Personal service (where someone hands him the papers) is obviously preferable, but just like everybody else, she doesn't know where he is.
My suspicion is that she filed in order to have everything teed up to serve him as soon as he's arrested. After he's served, he'll have 30 days to file an answer before she's entitled to a default judgment, and after a default is granted, most courts will force her to wait another 30 days before having a final hearing (if the waiting period has expired at that point; it's a "whichever is longer" situation).
With respect to alimony, it's true she has a job, but what's not clear is whether he's earning to his capacity. Tennessee alimony law considers fault, although it's primarily based on the obligor's ability to pay and the obligee's financial need. I would suspect alimony will be awarded in this case, although perhaps not a huge monthly obligation because they were hardly wealthy.
MOO but she may feel like filing for divorce is the only thing within her power at this point to say that what Tad is done is NOT okay and she does NOT endorse his behavior. She is probably tired of hearing how he allegedly got special treatment because she works for the school and this is her way of saying she's just as mad as everybody else, if not more.
I heard some concern several pages back that her filing would make it easier for TC to marry ET. The kind of man who would steal a 15 year old child to "marry" her is also the kind of man who isn't going to care one single bit that bigamy is illegal. And until the divorce is finalized, they're still married anyway. But it's not like if TC and ET applied for a marriage license, there's some federal database that would flag him as already married. That just doesn't exist. Of course, they would probably creep whatever county clerk out due to the age difference and I doubt they'd take that risk even with fake IDs.