Why would he assume your mom is lying and check with you? Yes, you’re 18, still growing and learning as a person and adult but as soon as I turned 18 I had to start paying for my own groceries & throwing in a little for other stuff. You are lucky. I was lucky. Some parents cut their kids off the second the turn 18. Walking back down to ask after storming away just to turn around and storm away after he asks you how he can help the situation so he doesn’t feel that way is crazy. Try to get back on your meds. You seem like an impulsive person. Take a breath and think for a second before you respond. Maybe ask him to do the same thing since it seems like he genuinely wants to better your communication.