My thinking is that the post is an attempt at emotionally manipulating her children. If I were a judge seeing this in court in association with a child custody dispute, this would definitely lean me in the direction of keeping this person away from the children - in written and spoken communications as well as in person.
IMO, the writer of that FB post hopes her children look for communications she may post there and she knows that it is the rare child who doesn't painfully miss their mother when kept away from her, so she is attempting to use that pain to:
(1) relate to them on that level ("I was kept away from my mother too, so I know exactly how you feel" - paraphrasing);
(2) demonize those who are making that happen (her ex-husband, his family, the courts and associated officials);
(3) raise herself above those she has demonized ("I am more in touch with God than they are. I see the larger plan"); and
(4) to appeal to them to continue to believe they will have her in their lives ("I know we will be together someday" - paraphrasing; this is particularly manipulative as it directly appeals to that heartfelt wish of a child to have both parents closely active in their lives).
If she wasn't incredibly manipulative - despite the cost to her children - before LV's association with CD, she has become a near-master at it under their tutelage.