Breastfeeding problems

My 18 month old Still nurses at night time and nap time so only twice a day but she wants to nurse all night long and I emotionally cannot do it anymore but she refuses to drink any other milk like cow milk or anything like that I try to give it to her in a sippy cup but she will not take it. So my question is - can I just stop breastfeeding cold Turkey even if she is not getting any other milk in take?

Side not - I've always had promlems with her eating in general- solid food, baby food whatever. she barely eats ever so I always let her nurse because I knew that was one thing that she would get but I want to stop that completely isthat something I should do even though she refuses milk and barely eats as it is?