This is not something I "brought myself" to do after some strange revelation, but it is something I do occasionally because my husband likes it.
Examine the constitution of your semen. Taste it yourself. Swallow it yourself. Don't ask her to do anything you wouldn't. If it smells or tastes bleachy at all, start cutting your salty foods and get on the fresh fruits and veggie train. If it's chunky, get yourself a big bottle of water and get hydrated. If your semen isn't an unpleasant consistency or taste, your wife may be more likely to swallow it for your pleasure.