Feel like crap

Ok so my bfs mom lives with us. We all went to a family birthday party yesterday. We had already had a very long day on Friday and had to be up early Saturday for his daughter's performance and then on to the birthday party. Well by 8 o'clock at night i am tired and done. My older son got hurt in the jumper knee to head. All the kids are older than him like 13 and 14 years old he is 7. I got upset and said let's leave. So i am pissed and then they decided to bring his cousin's daughter home with us too. I am just super annoyed by this point. His mom yells at me from the back seat relax .. it was an accident. I was annoyed because they squeezed everyone in the car . His mom says as we get home shes leaving tomorrow. He thinks she gonna move out. I said i will leave and he said no. My mom leaves she leaves. It's you me and our children. We need to work on this. So i feel like crap because i would never come between him and his mom or the reast of the family. I know I am gonna be portrayed as a bi ch . I don't know what to donor how to feel. Unfortunately this is not the first time something like this has happened. Am i crazy to just want to walk away with my boys? I love my boyfriend and we have came along way in the almost 6 years we have been together. Any words of wisdom... sorry for the long post.