Tough one trying to come between a girl and her BFF. I'd say rather continue to spend a lot of time with your daughter (even if Tina is there too) so you can keep an eye on the situation from close up.

Don't keep her away from Tina, she will encounter such people in life and that's a way how to learn to handle such person. Build her self-esteem and her self-worth.

On the other hand, boundaries must be set. Tina can be visit certain times, but not all the time. Be firm about it. That is also a way that your daughter will learn that certain times is family time and certain time if time spending with friends, exactly like she know that from 08h00 until 14h00 is the time she is at school Monday to Friday and for example Sunday 09h00 to 10h00 is time for church.

Let her know that it's not because you have something against Tina, this is how your family do things. Take Tina to some family gatherings, but again, not to all, decide beforehand. Let your daughter understand it's not a given that Tina always will go along. That also gives Tina time to spend with her family.