My Mom Wants Me To Give My Foster Son Back

Thank you guys for helping me so much with advice. Me and my mom just had a fight. I'm still trying to get my foster son used to everything. My mom wanted us to come over yesterday for some wine. Since it was just me and my mom I didn't think my son would be to stressed. My husband dropped us off and we had an ok time. Until my husband ended up getting in a car accident at night. Our car is fucked. He said he would pick us up tomorrow with a rental. We stayed the night at my mom's. I feel like a terrible mom because it slipped my mind about his bedwetting problem. IDK why I forgot. I was so worried about my husband. He was to shy to say anything. He ended up having an accident on my mom's couch. I apologized to my mom and gave her money to get is cleaned. When my husband got here she pulled us both aside and goes " I know you want kids. I really want to be a grandmother, but I think you guys should get a more normal one". I asked what she meant by that and she says "He's 14, he's too damaged. It's too late for him. You can get a younger one! That would be a better fit for you guys". I go " A better fit for who. Us or just less embarrassing for you!" She said " Stop making this about me". We started arguing and she started giving me reasons to give him back and get a younger more normal one. I told her "If you don't like him we just won't come around anymore". She goes "Fine! Don't say I didn't warn you". We drove home. I feel like this is all my fault for forgetting and I can tell my boy just feels even more unwanted. I want to do right by him! Now me and my mom may never talk to each other again. Honestly as long as he's okay I'm fine with that but I feel like this is all my fault.

Also this conversation didn't happen in front of him but I'm pretty sure he heard it by how he was acting in the car... I feel awful