Different states have different rules. I know here in Florida, only a judge can dissolve a marriage. Mediation helps cut a lot of the costs and usually helps to work out many issues (custody, alimony, assets).
As for your other question, Florida is a "no-fault" state both with regard to employment termination (unless it's a Federal violation) and divorce. What this basically equates to regarding divorce, at least from my reading, is that it doesn't matter whose "fault" the broken marriage is; as long as both parties agree the marriage is irretrievably broken, a judge will dissolve it. Of course, there can be many, many other factors that judges consider, such as education levels of the parties, children, assets and length of the marriage. Other states are different.
I think your best bet would be to contact an attorney. At least here, mediators don't look out for any one side's interests. Their objective is to settle. Usually your lawyer is involved with mediation, as well. I'm not in any way trying to give you legal advice. Rather, I'm encouraging you to seek it from a professional. The laws are so complicated and many are left up to interpretation from a judge. Plus, the laws change so frequently due to reversals at the appellate level, unless you subscribe to certain law books and read them weekly, there's no way the average person could keep up.