Jealous sister-in-law?

Ever since my husband told his sister we are having a baby things have been off with her. Her first reaction was to call us crazy. Since then she has talked bad about me, saying my husband shouldn't have to deal with my expensive taste in baby stuff, (I was very confused by that one, considering I like to buy mostly secondhand) and asking, "why did you even get her pregnant?" She is a year older than me and three years older than my husband so I'm not sure if she just wishes it was her or what. I'm not sure I can even be around her at this point after hearing everything she keeps saying about me. Any advice?