Is this some more signs she is a golddigger?

Im now very concerned that this girl is using me and am going to break up with her. I just want to know something first. Over Christmas I foolishly spent my whole check on her 2 daughters. I got them psp, makeup, pogo stick. I know I spent at least 300 dollars for each girl. I even gave her mom 40 dollars on a gift card to try and win some brownie points because I havent met her yet. When we was in the car I mentioned something about how a lot of stuff was coming up and our anniversary was coming up in february. She didnt even remember that and apparently her oldest daughter who was with us at the time got upset over it. Apparently she told her grandma and now her grandma says she cant accept the 40 dollar present from me. And my girlfriend got upset because apparently I didnt spend enough on the girls. She was trying to outdo her so called ex who she is divorcing. Said my presents looked bad compared to his. I was hurt but i feel like I cant say anything to her about it. Please any advice would be helpful