You're going to have to take a step back I'm afraid.
Observing a child behaving poorly is really difficult, not denying that. However, aside from offering constructive support if it's wanted, attempting to gently explain that the consequences of such behaviour might lead to longer term unhappy outcomes (such as homelessness, loss of relationship with child etc), there's not much you can do. I wouldn't issue forwards criticism and threats or bullying as it's simply counterproductive even if you're angry.
I don't think it's reasonable to have expected them to meet you when you had your afternoon off unless you'd already negotiated it and your son had no business wading in to say you're upset, that's just manipulation and triangulation and drama of everyone. Try not to do that. Having a dramatic, upset, bullying, critical, parent is the first thing that would repel anyone from turning to you for help. Try to be kind because being kind is the most helpful thing that could resolve problems, don't be a mug though.
If your daughter's feeling overwhelmed, mentally unstable, or depressed, or is just straight up feckless, they're going to need to accept that they need extra help, support, and implement some systems so as to be able to function - not easy. Can they get some counselling / relationship counselling somewhere? There's organisations that specifically offer counselling for transgendered people, for example in London - Galop, Stonewall, London Friend. Dunno where you live though.