All the evidence shows that children benefit from having more loving adult figures in their life. 1 more won't hurt.
You can't just rip your daughter away out of jealousy, especially if you're not prepared to sacrifice prestige (prestigious school) and put in actual time and effort to spend time with your daughter and make it enjoyable for her. (Yes, she doesn't like your company atm, but your approach of chucking her into boarding immediately is hardly going to help that.)
You asked for perspectives. I was your daughter, growing up in between worlds, and my mother (who claims to be loving and is/was, but also emotionally stunted like you) always had odd solutions like you, mostly throwing money at problems.
"I don’t think she is genuinely happy tbh" is bonkers. Of course she's happy. All children (even teens) want is a stable, loving figure. That makes them happier than all the fancy stuff in the world.
Just because she's a troubled teen doesn't undermine that. If anything, it makes it more important. I still remember the year at 16 or 17 when my dad was laid off from his CEO-level job and was actually in the same country as us. My parents probably find that the harshest year to look back on, yet it was genuinely the happiest year of my entire teens.
Even then, she may have underlying fears around the temporariness of her dad's gf, or she may have mixed feelings of resentment towards you... Still, none of whatever Evil Stepmother move (even though ironically, you're the birth mother) are planning is going to fix that.
I 100% get the boarding advice for education & career prospects in the long term, but consider 2 things –
- Now is probably not the time. She'll probably gain more mental health issues + resent you for a long time.
If you're afraid she'll get "too used" to her current situation and want to rip off the band-aid and bring her over before it's too late, perhaps consider a transition period of actually living with your family (as opposed to strangers, no matter how lovely you find them) first.
- If she's happy where she is, maybe it might be more pragmatic and beneficial in the long run for her to stay there. Boarding school doesn't mean your life is necessarily going to be perfect or even good.
I know plenty of boarding school people who have stuffed up their life badly (some literally, i.e. died young, by their own hand) because of childhood dysfunction.
Your family loves you because you're you. Love is unconditional.
Whereas at boarding school, older students and teachers often take a special shine to certain students. And survival (emotional & practical) depends on gaining the favour of teachers and students around you.
No matter how cosy a certain boarding school looks like on the outside, boarding school inevitably forms your worldview of love, attention etc as prizes linked with scarcity and competition.
Of course less so for those with a present, loving – i.e. actively shows you they love you by making you happy, not just claims to love you – family, with no adverse childhood events, but I still believe they absorb that worldview.