Husband causing me stress

He's been great and not so great since we found out. Today is a not so great day where he decided to go to the bar all day. I saw a message from his ex who he has kids with saying hope your OK. He obviously did not pick up his kids like he was to and made some bs excuse as to why not so he could continue to drink however I am angry that this type of text was sent regardless. I'm trying not to lose it too much over baby but I am ready to let rip on him. We have a Long and negative history with this person. Am I being unreasonable/oversensitive that she believed his bs story and messaged that. I know there is no love lost there and have no worries in that sense but I feel it is inappropriate to have a message like that come in