I signed a buyer's agreement in Texas with my realtor.Together we didn't find anything.Can I be sued?

I found my new home by myself one day. The next day another realtor took me to a close by neighborhood (same builder).This realtor ended up on my contract that I signed since the builder knew about her. Now the first realtor is threatening to get the 3% commission from me since she's not on the contract and the builder won't put her on since she never came out with me. I asked her if I could go out looking without her and she didn't balk so I'm assumed it was ok to look at totally new homes without her. The 2nd realtor tells me the buyer's agreement has no legal standing but I'm worried. Can I be sued/am I liable?