Take the emotion out (or at least try). Head not heart.
I can't remember if you had engaged an a lawyer yet. If not, do it on Monday as Yorkie said.
Keep the text and evidence that you've been blocked from the children phones. Screen shot everything. Your kids are too young to have blocked you themselves so it is most certainly your W doing it.
If eldest child said he doesn't want to see you then that is something you need to talk to W about and put together a plan. Your child is hurting. You need to work together not against each other to ease their pain. I know it's tough. There is fury on both sides. Put that aside, hopefully your W will follow your lead. One thing that worked for a friend was even when her D said she didn't want to go see her dad, even when she clung to her legs, she forced herself to her go anyway. But, she was willing to put her ego aside for her daughter. I doubt that would work in your case, but that's when the lawyers come into play. When you have the kids, make it so damn much fun that they will never want to leave your side. Also, don't bad mouth your wife in front of them.
Others here would disagree, but when it comes to the kids I will break the NC rule. Children are not pawns.
If you do respond, she will most likely keep the texts as evidence so make sure you choose your words carefully.
"W - I am unable to contact the children's phones. This may have been by accident. Can you check their phones and unblock me. I am committed to working with you in fostering a positive coparenting relationship and ensuring that this difficult period is as painless for them as possible. Can you let me today when its done."
That way there is no blame, you've made a perfectly reasonable request, and you show that the focus is not on the R but on the children.
If no response, then you take the text with you to your atty on monday as evidence she is keeping the children away from you.
