Toddler broke my son's Xbox and now he wants to move in with his dad

Me and my husband aren't doing good financially. I've always struggled. My ex is extremely successful and has a big house. When we split up we were both on government assistance so clearly I wasn't getting alimony. He went back to school and got his nursing degree so now he has a lot of money. I have a 3 year old son and he shares a room with my 15 year old son. It gets cramped but we do our best. My son's dad got him an Xbox for here a couple years ago. My son has been getting irritated a lot more with his brother lately. He thinks everything is his. He took my older son's notebook with his drawings in it and said mine when it isn't his. My son took it back. He went into his brother backpack and took it again and colored all in it and again said it is his and I had to explained not everything is his but my older son was angry because his drawings were already ruined. My son had a water bottle and opened it and poured it on my older son's Xbox. The Xbox is fucked. My son got really angry and said he needed to take a walk because he was about ready to HIT his 3 year old brother. So he took a walk and said he needs to move in with his dad. That did hurt my feelings but he said at his dads he gets his own room and doesn't have to worry about someone destroying his things. He said he's going to be honest he does not like his brother. He didn't ask for a little brother. He didn't want a little brother and now his brother just destroys his things and he's upset. I don't want him to leave. I feel like a failure as a mother. I hate that I don't have money. His dad bigger house is clearly more appealing. I know it's not good to compete with your ex but I just feel sad that because of my financial situation he would rather be with his dad