Weird friendship

I used to be bff with a woman when we worked together 4 years ago, I even got her a job where I work now. Since becoming pregnant she has distanced herself and has been saying really weird and hurtful things to me about my pregnancy. So the past 7-8 months we have just been coworkers and have kept our distance. Now all the sudden she is all over me, touched my belly for the first time, hugging me, calling the baby "her nephew" (we don't know gender) and saying she is going to babysit all the time. She wants to take me baby shopping on Friday. My husband and I don't want her babysitting bc she is 40 and doesn't like children, no experience w them and the only reason we think she's interested in this one is bc we were close enough friends she has an in and she's going through personal stuff about turning 40, never getting married, never having a family. Idk how I'm going to handle this bc I only have 5 wks left and I don't want to make things weird at work but she will never be alone with our child.