@tobyharba I empathize with you on this subject. My gf and I have a 3 yo boy, who is the most energetic monkey I've ever seen (climbing every gate, wall, fence, chair and couch since he was 6 months old). She also has two boys, 11 and 14 yo.
I also WFM and she has been a SAHM since she moved in with me when she was pregnant. Our little one was a month early and also had a rough pregnancy. Fast forward to him being 3, she lives on her phone (Netflix, Hulu, Prime Video, etc..). There are other circumstances involved with her (gambling and drinking) but I told her more times than I can count to put her phone down. I wasn't looking for her to give me attention but give our child attention. When I work, he just wants to come in my office and sit with me. When he isn't with me, he's destroying the house (not just making a mess with his toys). When it was apparent that things weren't changing, I moved my office into the living room where he spent his time and really did double duty with him while I worked.
It's demoralizing to work so hard on maintaining your job performance, keeping the house clean and taking care of the kids to only watch your support system not actual support you. Demoralizing, frustrating, at times infuriating and especially depressing. It's hard to do all that and stay on top of your own well-being.
I don't really have any advice for you that hasn't already been said.. just know that you are not alone. Do everything you can for your kids! If it requires a change in your everyday approach, do whatever it takes. Stay positive and take a day at a time. Enjoy the moments of laughter with the little ones and relish on the marvel of them growing up.
As for my approach, I made her and her two kids leave and kept our little one by myself. For me and him, it's better that way until she gets better. My decision was based on the other circumstances though.
Just be honest with her. Tell her how you feel.. how she makes you feel. Ask her honestly to listen to you and empathize with you. Keep your head up! Hopefully things get better for you.