Ok so this is still about choice but it is also about offering some help.
First I have to say, I AM NOT AN ATTORNEY and THIS IS NOT LEGAL ADVISE
That said though there are some things that you can do to help yourself if you find yourself in a situation.
First and foremost know that, just because you feel its right or wrong does not make it the law. That is a valuable lesson to learn from the beginning. Any attorney or judge that you might have to deal with for one reason or another are confined to the parameters of the law. Moral and ethical are not the law either. Also everyone will always feel like they are right or have been wronged however they will not always win.
If you find yourself in a custody situation there are a few things that you can do to help yourself:
1. Try and work with the other parent, remember it took both of you to create your child or children and they will be much better off it their mom and dad can get along so put aside your hurt and anger and put them first.
2. I know it is not always possible to work with the other parent whether it be criminal issues, domestic issues, ect., do the best you can. Do not bad mouth the other parent, you would be hurt and upset if you found out they were bad mouthing you in front of the child(ren).
3. Keep a journal, write down if a visit happened, did not happen, why it did not happen, they were late or early, if they dropped off to you early. Be proactive and take the few minutes to write it down with the date and a time.
4. Do not be petty, they are not going to be perfect and neither are you so don't forget that.
5. If you truly believe there is danger than stand up and say something be proactive, however you do not want to cry wolf all the time.
6. If you do believe there is danger for your child, get proof. The "well so and so said they saw him/her here, or I have heard they are using or are in trouble with the law. You will need proof. You can go to most court houses and in the clerk's office or a viewing room look up the person's name and see if there is anything there. If there is write the file number down, ask to view the file or pay to have a copy of the file. Most records are public. If someone told you information are they willing to testify in court, if they aren't then it is just heresay.
7. DO NOT talk to the child(ren) about the adult issues. They already know there is a problem they don't need to hear you and they do not need that much information. They also do not need to feel as if they need to make a choice.
8. Sometimes you need to just agree to disagree.
9. You can not withhold visitation if the other parent is in arrears for child support. If you withhold the visits for that reason alone and the other parent has had enough they can file a show cause motion and you could find yourself being the one in trouble.
10. Never use the child(ren) as a pawn or a means of control. So things did not work out that is not your child(ren)(s) fault so do not make it their issue.
11. There is "Best Interest of the Children" which in most states is 13 factors although a few other states have 14 that are looked at by the Friend of the Court and the Court when deciding custody. You of course can google Best Interest Factors for child custody and you can even put in your state.
12. Always read what you are signing and make sure you completely understand what you are agreeing to.
Again, I AM NOT AN ATTORNEY, THIS IS NOT LEGAL ADVICE. This is just some helpful information. Remember knowledge is power and your child(ren) should come first.