do lawyers have to look into information from a client to see if it's true, before using it against someone in legal write ups?

My ex's lawyer is submitting things my ex says about me, that are not anywhere near the truth Because I don't have a lawyer, no one is listening to me about the accusations not being true. I am losing my children, and money I don't have, because these accusations are being treated as truth, with nothing to back them up.