Be a man for fuck's sake.

Marriage isn't always a perfect balance between what you put in, and what you get out. Right now your wife needs to be the priority. Let her be... Help her to be. Any pressure you put on her now to come home (and help with what you should have no trouble handling on your own) could have life-long consequences to your marriage.

Her dad is dying. Show your wife the love and respect she deserves, and stop thinking about how it affects you. This isn't about you.

To answer the question from the subject line - however long is needed.