OK, that's rough having do deal with the little guy. Poor kid has had his world turned upside down and he doesn't have the skills to deal with it. A therapist would be an excellent idea.
Good job on ignoring the baiting text from her. That was awesome and I am proud of you. Obviously, S3 is your #1 priority. And since there is nothing you can do about his time with her, all you can do is the best you can do while he is with you. Obviously, you've been doing that, and then some.
But just keep your chin up. Things will get better. As you've said before, you are his rock. And he will remember this later!
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018