My mother-in-law likes my husband's ex-wife. They may still be in touch. Is this even normal?

I understand that she is an adult and has the right to communicate with whomever she wants, but I think this is disrespectful to me as a daughter-in-law.

It offends me. She doesn't like my photos, even the ones she shares with her husband. She is a very affectionate woman and likes everybody. And if she doesn't, she doesn't show it. So she doesn't like me since she doesn't like me?

How do I respond to that? Why doesn't she like me then?