Am I overreacting about this?

Sorry in advance if the grammar is bad. Back story is i have been seeing my boyfriend for over a year. We both have a child around the same age and my child is very attached to his family since their dad and his family aren't involved.

Ok so boyfriends mom is sick and in the hospital. I have offered to go with him to see her or even watch the kids so he could go up there and see her. He says not to worry about it and things will be fine. After things take a turn for the worst, he tells me he wants me to come to be there for him. I get to the hospital and end up watching his daughter so his ex could be in the room with him while his mom died. I didnt even get a chance to see her or say goodbye. His ex hadn't been involved with his family at least since we have been together. I am trying to not be upset about it considering he lost his mother and I dont want to be selfish but it really hurt my feelings. When he came out with his ex and told me his mom was gone I kinda lost it and started crying and he kept asking what was wrong bht I didnt want to cause a scene there or talk about it in front of his ex. Am I overreacting by being upset?