Last night the washing machine broke down; we needed a new one and have been saving for a nice front loader she has always wanted. She told me to just go get the cheapest one out there, because money is tight. This led to a discussion of our finances. We've spent about 9k on her graduate school expecting to recoup it because she's gets a 5k raise once she completes the degree. Earlier in the week she mentioned using a loan to pay for the rest of it, and I asserted that considering the climate that she should go ahead and get the loan. It made her pretty mad!
I would suggest neither. The graduate school plan, as you yourself state, was for her to be in a better financial position to help the family. Since she is, in fact, running AWAY from the family now, this is her economic burden to bear, until a judge says otherwise.
You should suggest that she take out a personal loan for this, and that you won't be co-signing for it nor paying on it.
I would strongly suggest that you get some concrete evidence of an affair, as soon as possible. It will strengthen your hand, help you better understand what you are dealing with, and will buck you up to take these strong steps that I'm advocating.
