It's your friend. Search this site for techniques. I would have not sent that message. Let her send those "feel good" texts; just ignore. You clearly know they are just a show. It's also giving her unnecessary attention, and after all this time, she will NOT change nor will you force her into any change (like calling vs texting). 

DHs kids were blocked on my phone for many years. Add to that, DH told his kids to leave me alone. They are no longer blocked but they don't reach out, so all good. I do NOT do social media with DHs kids...blocked there, too. DH also saw them away from our home for many years....I am finally comfortable with some of them coming for short visits. I busy myself in my studio or I make plans with friends.  DHs kids are a "non" thing for me these days. Very few minimal impacts these days as I have good boundaries in place and have zero expectations from any of DHs kids. In my world, I am DHs wife. He has kids but I am not in relation with them. It took a while for me to get to this place.....I suggest you begin disengaging and implementing boundaries that will bring you peace. 

she knows what to do to keep daddy happy. ignore, ignore, ignore some more 

My SD, too, did just enough to make it look to DH (and outsiders, as her and her mother's reputations/their false narrative is gold to them) that she was an angel princess, all the while practicing terrible passive aggressive behavior that was very hurtful at one time. All the while, SD would always be sure to do the smoke & mirrors show and ask DH how I was doing and to tell me hi. When DH would confront her about her clear hatred of and bad behavior toward me, she would cry hysterically and deny it. In person, she'd put on the sweet SD show face-to-face until her father left the room or wasn't looking. I always likened it to a young bratty child (although SD is 30-ish now) at a dinner table acting very sweet and then sticking out her tongue at you when Daddy turns his head. lol. HCBM behaved similarly early on, obviously taught SD the ropes, and assured me that she had shown nothing but kindness to me. 

All of this is to say: Stop. Just step off the crazy gaslighting train. It's maddening and stressful. Trust your own experience and act on that. Like others have said, disengage. 

*I once told SD, "If you don't like me, there's nothing I can do about that. I'm not going to wring my hands and stress over it. If someone doesn't like me, they don't like me." BIG SHRUG. She went silent, as I had broken through her BS to her face. It probably annoyed the hell out of her that I don't give a crap, and I am under no obligation to DH to even communicate with her. I wasn't playing her game. It was after that conversation that she stopped asking DH how I was. wompwomp.

Disengage from all the dysfunctional garbage from SD.   It's simple to do with a little practice.