There are an awful lot of women currently posting over on Relationships who have recently discovered that their husbands of many years (and fathers of their children) have been leading a double life. Internet porn, online dating, shagging secretaries, EA's with exes, debts, gambling, weed addiction, you name it, - if it's available, someone will take advantage of it. And lie about it to their nearest and dearest.
Really don't see why the scenario in the OP is worse. You might feel like a complete muppet, but it ain't rape.
Blimey, I inadvertently shagged a right-wing public-school bastard at Uni. By accident. Honestly. Came on during our one-night stand and he wanted me to launder his sheets for him the next morning. Honestly! Ungrateful swine.