OK, to reopen the divorce to argue for a change of custody what you need to do is prove to the court that there has been a "significant change of circumstance" and consistent negative influence and contempt of court can be considered a "significant change of circumstance."
1. Courts don't give a crap about hurt feelings and emotion so check it at the door.
2. Courts deal in facts, be concise, factual and have proof.
3. Courts like details. If you have not already start a journal and include every detail regardless how silly you think it is. Include times, dates, exact quotes, people who witness or heard statements, copies of any contact, email, voice mail.
4. Before you forget write down everything that is not already documented.
5. Get all your information in order in a factual, concise, chronological presentation and present it to a lawyer and tell them you want a hearing to re-open to readdress custody.
6. Take control of the matter and divulge NOTHING to your ex. Make her pay for her own attorney and give her NO information. If she asks tell her to contact your lawyer or hers.
7. Be deliberate and not emotional. Make no threats, make no statements to her. Tell your child you feel you are being treated poorly and it is not her fault but you think you need a judge to listen and decide. Tell your child nothing about what is going to happen, what you are mad about, what you are going to do, what the mother is going to do or be negative or divulge details. It is her mother and she still has allegiance to her mom, as she should, and will spill your plans, info or statements when the guilt trip starts. Keep them separate to any and all details.
8. If the court agrees there is a reason to readdress custody you have won 90% of the fight. Go into the custody hearing totally prepared and not emotional. Figure that they can and will ask you ANY question so have an answer.
9. Do not let people tell you you cannot get custody or that mothers never lose custody.
10. Be prepared to write a big check. Also do research. Look for child custody decisions and laws off the internet including State supreme Court decisions, appellate court decisions and it does not have to be in Maryland.
11. Take no prisoners, it is your child too. This does not mean become an a-hole. courts act as "a wise and concerned parent" and you should too. Courts also despise whackjobs who shriek, push illogical and juvenile arguments or ignore their orders.
I am not a lawyer but I won custody of my then infant son 11 years ago. This is what I did and it worked and I did a ton of research and planned my attack myself complete with court precidents and cases to cite. I used the lawyer simply as a tool (ironic because he was a tool) to navigate the court.