dealing with jealous person

So I have this person in my life who is family by marriage. I have little to do with her because she is annoying and tries to copy everything I do. I no longer talk to her. She is on my social media and so I post up as little personal stuff as possible so I don't have to deal with her. there has been several occasions that she has acted out over events in my life that (while good events) they were kind of out of my control (like pregnancy, moving, living near the beach). So on. I've known she has been jealous for a while and again I do my best to not associate with her. But she starts texting me the other day about family stuff. So I start responding and then out of nowhere she is like "I envy you. I'm so jealous!". I don't know how to respond. I don't know what to say. I can't help we have different things going for us. and it's really annoying that I cant say anything about my wants or likes without her copying me. I just don't know what to do. I sometimes feel like she is trying to compete with me. thoughts on how to handle this/her?