SIL not MIL

So my SIL hasn't seen my son for 3 months, even though she only lives 10 minutes away. She's always been awful at coming to see him and her dad has to basically guilt trip her to come see him, she spends more time with her cousin's daughter. Now she's out of a toxic relationship and got a new job and apparently has turned everything around... She facetimed us on Friday saying shes coming over today to my son. This morning I texted her asking what time she's coming, she read it and didn't reply. Then she posted on Facebook a mother's day post to her dog, that she'll be spending the day with him... so my son isn't as important as a dog you spend all day everyday with?!?