This might be childish but....

So, I know this might seem childish to some but I know someone will agree. My mother in law, who didn't like me for an unknown reason and  decided all the sudden when I got pregnant she wanted to come around... problem is she still stays in contact with my husbands ex wife whom they share no tie to. I'm currently pregnant with his first baby her first grand baby! But I'm not really comfortable with the fact she still keeps contact with his ex wife whom lives 1000 miles away, and has only come around because I'm pregnant. I personally feel like it's disrespectful to myself and my husband. How would you address your concern without seeming petty!? or am I wrong for feeling this way...