If you found out your spouse cheats on you, personally, how long will it take to act rationally?

It depends on the individual, and how you found out about it. Catching someone redhanded is more shocking than, say, intercepting an email. Despite the smack talk on tv and the country songs, at least TRY to act rationally. You will, of course, be emotional, just don't go shiznit super psycho and destroy property, stalk, or anything like that. I went "minor psycho", slapped him, threw a phone, a few other small items, and just felt like absolute hell. Then time went on and I realized I was wasting energy on a complete jack. So, even though a little part of me still loves him, I know he is a jack and I am much more rational than emotional now. That took about 4 months for me.