W.P.
Dear D.:
If she had it on speakerphone, she obviously wanted you to hear it. In Texas you can record a conversation, if one party agrees to it, the other does not have to be informed. And it is your phone, so I guess you are the party in case of your daughter. Depending on the equipment you have, you can record a conversation with it directly or you need an extra piece (usually under $100) for the computer or a tape. A VCR should work, too, even if it is just sound. That should give you evidence you may need. Also take lots of notes with dates (if needed times) and what happened. Get legal advice, but start doing this right away. Try to remember as much as you can with as much detail, possible witnesses, etc. You did not mention your custody arrangement, but either way they seem to be out to paint you as a bad parent.
If your daughter cooperates, try to get her to ask for more detail during such a phone call. If that woman says you're a liar, have her ask: "What do you mean, when did she lie? What makes you think that?" The more ammunition and detail, the better. And be there while the speakerphone is on. A taped phone call is legally valid, if backed by a witness.
I am not a lawyer, but I read the Texas Penal Code regarding that due to similar issues here. My lawyer told me that keeping a log is good, because likely the other side does not and then they cannot object to details you mention because it was too long ago. And ALWAYS stick to the truth. You can write: "I was under the impression that..." if you felt that way. If it turns out that the 'fact' was untrue or ambiguous, your impression was still true. If you heard someone say something, quote or relay indirectly, listing that person, so they know it did not come from you.
Gear up for an ugly one...
W.
(father of 8yo boy)
P.S.: My ex took two of the three prepaid cell phones for my son away. Well, they got 'lost'. Would appreciate more info on your rights in a private message...