I get how you feel. There is one man I was involved with for a few years and the things he was doing ... just, wow. The day that everything went down, I was doing the "who are you?" because clearly I had no idea and paid dearly for it. I really don't want anyone else to go through what I did but I'm sure he's done it again. And again. I don't know who he dated after me, who he is with now, nothing, but if I did I would be tempted to warn them if I thought there was the slightest chance they would listen.
Do you know anything about her personality? That is something I would take into consideration. Do they have a receptive personality, the kind of person that would hear you out, take an unfiltered look at their situation and see if it anything applies? Or are they a he would never do that to me, I'm smarter than you are, he loves me more, he's changed and every other excuse attitude type. Yes he would, probably not, I doubt he is capable of loving anyone never mind you and not a snowballs chance in Hell.
I had a friend who was contacted by her fiance's ex-wife and she warned her that he was nothing like he seems, he's an abuser, he's going to start isolating you and cut off anything that doesn't involve him, someone else had warned her too but she didn't listen, everything. She married him anyway because he "loves her sooo much and they have something so special" along with some Jesus tossed in. A few months later he was beating both her and her child regularly. It took her years to get out of it, she lost a lot of what she had worked for and her child was totally screw up. Oh and she now had a CPS file and a couple of serious arrests on her record so good luck with reinstating that professional license.
About "changing", stopping a behavior doesn't mean someone has truly changed. That comes from within. Many people can stop a behavior when it suits their needs and don't have any compunctions about doing it all over again when their situation changes.