Which title is better ?

A Monstruous Betrayal is my favorite of the ones you listed. However, it sounds like a title that I've seen before on a harloquin romance novel. You might want to employ an even more unique sounding title using different words that essentially mean the same thing, such as "Beguiled" or "Hoodwinked". You could even come up with a clever phrase, like "Trapped in the Web" or "Lured and Hooked". I don't know, just some silly suggestions. It's your choice, but I recommend coming up with the most unique title you can, because it will be more likely to catch a publisher's eye.