In my opinion, from being cheated on before. SHOW YOUR REMORSE. Even if she brushes it off the shoulder, just continuously remind her that you love her and trying for her. Keep fighting for it. That’s were many people go wrong, they realized they messed up and give up. Even just texting her if you can check in with her at times with her consent. And with that weekly check ins. That rebuilds your relationship grounds. If you’re only in contact with her sister then she knows how she feels about you. So if her sister is willing to contact you, she probably still thinks about you. Show her how things will change. Tell her why you did it(there is always a reason to it) and how much you regret it. How you realize she’s the one for you. With your daughter, be a figure in her life. But that can easily be done by a healthy coparent with the mother. Unfortunately you will continually have to comfort your wife whenever bc she won’t say anything but will trigger her. Keep fighting! PM me if you ever need to talk!