Is it just me, or are we experiencing abuse?

My husband believes I overly coddle our children and don’t discipline them for their actions. Our oldest has Oppositional Defiant Disorder (ODD) and often responds with “no” over the smallest requests. Typically, he becomes upset, but once he calms down, he apologizes and does what I’ve asked. Our middle child struggles with ADHD and anxiety. He has trouble sleeping and is somewhat less mature for his age. My husband, a combat veteran, has been diagnosed with PTSD since leaving the military 12 years ago. He often resorts to yelling at our kids, which has made them express fear toward him. Simple incidents, like a spilled drink, can provoke his anger. I've communicated my concerns, particularly regarding our oldest son, who now prefers to avoid his dad. There have been instances where my husband has physically dragged him when he refuses to go to his room, and he has slapped him for being defiant. He believes punishment is necessary, but I feel his approach has become overly harsh. Despite my efforts to explain my perspective, my husband insists I spoil them. Today, there was a heated argument between him and our oldest. My son ran downstairs and locked himself in a room, afraid his dad might hit him. In a fit of rage, my husband kicked the door down, and I tried to intervene. No one has ever told me I baby my children except for him. He’s now threatening to quit his job and leave our family, which terrifies me, as I wouldn’t be able to support myself and the kids on my income alone. I fear losing everything. I know I’m not in the wrong, and I've urged him to seek help, but he refuses, claiming it doesn’t work. I’ve been in therapy for years due to a difficult upbringing with a narcissistic mother who struggled with substance abuse—she has since passed away. Am I mistaken? Am I the bad parent here? I feel incredibly isolated, with no family or friends in our area. Is this situation abusive?