I have a girlfriend who's best friend I find out is keeping her drunk and seems to be using her for money?

My Girlfriends husband passed away a year ago since then her so called best friend has been getting her blind drunk every day and I feel she is manipulating her by keeping her drunk and giving her advice that I only think is for her (the manipulator) I think she uses her for money, she's getting a two free cruises and this girl never spends a dime! she claims she will pay back the money for the cruises but that's impossible she doesn't even work, she's said several times "I hope you don't think I'm using you." and I over heard her call me a gold digger and i've never asked for a dime. My question is, is there a condition that this manipulator has? getting her drunk and drugs (X) trying to run her life for her own benefit, and constantly trying to take all her attention, I think this girl is dangerous and has bad intentions..