There are very few things that I won't mess with. One of them is the bond between a mother and a son. Let me tell you that you're treading on some thin ice here because you're blaming his mom for what's happening with your fiance. It could be possible she has nothing to do with it. There are a couple of Santerian books easily available which can help you break the curse/hex that COULD have been placed; however, this is assuming something like that has been done. The nice thing about Santeria is that it has a lot of Christian/Catholic undertones to it, so the saints and incantations they use should be okay with your Christian background. If you and your fiance get back together, you need to take that shit to the grave! Don't ever tell him you performed any kind of spell work, hex work, or mojo involving him and his mother. That's a sure breakup right there.