Leave well enough alone, honey. Your ex monster in-law has a firm hold on her son and he seems to enjoy it. Even if you and your "soul mate" got back together, you'd still have to deal with the M O T H E R.
But I know you aren't going to listen to me. So buy Dorothy Morrison's book Utterly Wicked. I'm sure you'll find a number of spells in there that will help you out.