If the various "rules" you mentioned are the big problem, prudence might suggest easing up on them. Rebuking the sinner is only required when you think it will be well received and will actually correct the sin. Maybe you can strike a compromise where she dresses modestly at Mass and she could have a TV, even if you don't watch it and don't let your son watch it. If she doesn't have the faith and doesn't have the right motivation to comply with those rules, imposing them first, before she's persuaded of the faith might cause her to rebel, and if those are the only things standing in the way of creating a stable situation for your son, you might consider easing up on these things. You could think that you're responsible for any of the effects of her immodest dress, for instance, but if you break up, she's going to do that anyway. Lots of prudential judgment calls that you need God's help her to navigate.
Just think about being a worldling and then suddenly going from 0 to 60, as it were ... and feeling like you're now having to start living like an Amish person. That can be a shock to one's system, and might suggest a very gradual introduction of things, prioritized. As I said, maybe start with a couple things and ease into them. Once she gets used to one or two rules, it'll be easier to introduce another one, then another one, and over time (with patience), she might get there ... whereas abruptly imposing all these rules might cause her to snap.