I'm so sorry that you received the papers in the mail. What a coward to do it this way. Definitely see a lawyer and fight for what your kids are entitled to. Make sure you also are taken care of in the process. This would be a good time to nail down a formal custody/visitation schedule as well.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
