No judgement here, Joe. Although divorce is not God's plan b/t man and wife, He doesn't condone unfaithfulness of any kind. Paul believed God allows divorce in these circumstances. What she has done is not biblical, brother, but you know that.
I am so sorry for what you and the boys are facing; it is a spiritual battle that will require much prayer and diligence in the Word. I encourage you to continue in fellowship with other believers in a local church or men's group. Proverbs 14:7 -There is safety in the counsel of many. Seek it immediately with a mature pastor/counselor and others in Christ. Keep those boys in church - and let the pastor & staff and teachers know the situation, in confidence if needed, so they can minister to you/boys more effectively. Many larger churches have members who work in the legal field - seek legal advice from a Christian perspective. If none are in your church, speak to the local board of missions or local association office minister for references in that area. Many times they also employ licenced Christian counselors, too. Move with haste and Godspeed.
Father, I ask you to surround Joe and his sons with your protection from evil. Please give them wisdom to see the truth and discernment to recognize the lies from Satan. Hold them in your arms, so they can rest in your perfect peace, while You work in their lives to keep them safe. In Your son, Jesus' name we humbly ask.