What can I do about a jelous female customer who is trying to get me fired by making false claims and sending others to make false claims against me so my boss will fire me? Elmira NY

I work at a convenient store for a year now. Shortly after I started the job a yr ago a jealous woman customer has been causing me trouble by throwing tantrums about anything just to cause me trouble. Six months after an incident where she falsely accused me of shorting her money when she walked out in a huff leaving her change behind Less than $1 that she was given by me so she would leave. She wrote a letter to the new store manager complaining of falsehoods. My manager showed me the letter and said it was settled. I hadn't seen the woman since the letter that claimed she came to the store when I am not working. 4 weeks later this woman starts coming in on my shift every day and that same week my manager says she has 6 complaints against me accusing me of acting like I'm to busy to wait on them which is not true. I believe this woman did not get me fired with her letter so now she has people making false claims against me. My manager says that my job is in jeopardy because of this. My manager is putting me on a different shift now to see what happens. My manager says she is trying to help the situation and that I am one of her best associates. I was hired to open and this change in schedule is really going to effect my life. The female customer is trying to get me fired! The only pay I have is from this job. I have two animals that I care for. What can I do about this harassing woman? If she intentionally and falsely causes my job loss can I sue her?