Why is my daughters grandmother being evil and making up lies

My daughter is staying with her dad temporarily because of my dv situation with my ex but I have legal custody she just doesn’t live with me till I’m able to move to a safer place that my ex can’t find me but my daughters grandmother has been telling lies to my daughter and also telling her everything about how iv been beat by a guy and how he was in jail , and how I spent all my money and nothing to show for it yet I bought my daughter many things, she just altering many things and lying . My daughter is only 8 years old and I told her grandmother to shut the hell up on things she does not know about . I feel if this persists I will involve acs and I am already going to court to get my daughter to live back with me . I just feel disrespected on the lies and information she has been given , I don’t lie but I did speak to my daughter and we discussed what was going on but she even told me it she didnt understand much..she even told me her grandmother wanted to kill me at some point on a situation she lied about , she lied about some argument I had with my daughter dad, she said I threw something and it almost hit my daughter when in fact her dad threw it me and it almost hit her ..this has been going on for some time and she just told me her gma was bad mouthing me so I’m glad I was able to talk to her and set things straight. I see I’m going to really get a lawyer because this is unacceptable