Custodian Closed Ugma/utma Account

Exactly as the title says. I received a letter notifying me of the account after I reached the age of majority of 25. I initially set up a meeting with my bank to see if I could transfer the funds myself, but was told I needed signature from the custodian, my mother. I then contacted her, who stated this was a savings account she put in my name that she has been using for her business.I did call my bank and they told me the account was opened when I was 9. Unfortunately, she is adamant that the money deposited into the account was not mine but that of her clients and has recently closed the account and transfered the balance to herself somehow. How could the bank even transfer the funds into account not in my name, nor notify me of the closing? I haven't gotten a penny. We have scheduled a meeting at the bank a week from now, where she will be present, so I can try to clarfiy the history of the account, but I have confirmed it is UGMA/UTMA.

She has brought up the scenario of me possibly suing her, which tells me she's aware of the consequences, which I think is a last resort. If I do decide to pursue legal action, what would that look like/how long could it take/ what costs would be involved and what could I recoup. I'm trying to determine if this is worth pursuing at the cost of time, fees, and the relationship itself. In Texas for reference. Thanks.