Sorry to hear about your issue. Please let me make sure I understand this correctly. You have filed contempt? Is that correct?
Technically speaking, you don't need an atty. However, it's best to have one. It is not advised going to court without one if the other side does. Since you have filed for contempt, the hearing will be simply on that issue....Whether or not the person has violated a court order or not. You will be able to present any evidence showing that visitation and/or contact was withheld.
Despite the fact that you have some admitted issues, you have what appears a good position....At least on the surface. The bottom line is that there is an existing court order and people can't just arbitrarily decide that it's going to be changed, or they aren't going to follow it. If the ex MIL felt like visitation needed to be changed, then she should have done it through the court system.
As a general rule, judges don't like when people start making major decisions like this without the courts approval. Court orders are binding and unless there is something very serious going on (like abuse), then it's very hard to convince a judge why one has decided to not abide by a court order. The judge has sole discretion on the outcome as well as a potential punishment. Could be a fine, or even jail time, suspended. The last one of these I attended, a mother was withholding visitation, and the judge gave the plaintiff make up time, a stern warning to the defendant, and a 10 day suspended sentence. Judges take these contempt issues very seriously, as they should.
Your biggest threat is some type of unfounded charge against you....i.e abuse & etc. Be ready for it. They are going to paint you as a very poor father and then some. They might even go as far to say you are some type of threat and that's why visitation was stopped.
When you say the counselor is going to testify on your behalf....What are you going to have them testify to? I'm not sure I understood that part of your post. Not sure I would openly admit I was an alcoholic. You can be honest in your testimony without using that particular word. The judge may order you not to drink around your children so be ready for that.
Lastly, despite your shortcomings, you should know that as a general rule, courts do all they can to keep natural parents involved in their children's lives. Granted, some people may have very limited visitation, but it's rare for a parent to be excluded from a child's life. Hearings in J&D court are all about one thing....What's in the best interests of the child? Thus, ... should really pound home the positive attributes you possess and the value you bring to the relationship....i.e what positive aspects do your children realize from being with you? What about you being involved is in the best interests of the children.
I hope this hleps and please let me know if you have any questions.
Regards, and best of luck to you.