So, a little problem

So, I have this best friend and she is my ex girlfriend. I reached out to her not to long ago. Just to make sure she was okay. Cause I hadn't heard for awhile and now, I think she thinks we are going to get back together. That isn't the case at all.. Cause I'm very happy with my boyfriend, I'm the happiest I can ever remember being. I'm head over heels for this amazing man. My best friend she keeps attempting to flirt and she texts me all the time. When I sometimes tell her I've got to go. What should I do? Any help? I really need some advice.