Why does my boyfriend act so affectionate one moment and then become distant and harsh during arguments?

I'm really struggling to understand my boyfriend's behavior. When things are going well, he’s incredibly kind, caring, loving, and warm. However, during arguments, he transforms into someone unrecognizable—almost like a monster. He hurls insults at me, tells me to leave him alone, refuses to listen to my side, and makes me plead with him not to break up. He even threatens to cheat and hangs up on me while I'm trying to explain myself. I often find myself calling him multiple times, hoping he’ll pick up. What's causing this drastic change in him? Which side of him should I believe in? He’s been on medication for depression for the past three years and also has ADHD. His upbringing was challenging; he was raised by a single mother and his grandparents and has never met his father. He’s shared that growing up, he often felt like an emotional punching bag for his mom, which has affected their relationship, though it's slowly getting better. It’s clear he has anger issues. He often slams or bangs on the table when he loses at games or things don't go as he wants, and his table is actually broken from one of these incidents. To provide some context to our arguments, they typically start when I try to share my feelings. He becomes triggered and defensive, often dismissing my emotions, which makes me hesitant to open up. He’s 26, works full-time, and otherwise leads a normal life, but this aggressive behavior only surfaces during fights. There was one instance where a minor disagreement left me in tears while he chose to play cards with his friends, telling me I was ruining his night and asking me to go home. I even begged him, but he pushed me away. On top of all of this, we haven't had intimacy in months. He attributes it to his depression and ADHD medications. I can't help but question whether it’s normal for him to go this long without sex. I suspect he might be keeping things from me, like he could still be taking care of his needs on his own. We used to have a great and adventurous sex life, but suddenly, it’s come to a halt. Is his lack of interest due to his meds or could it signify he’s interested in someone else? Does this mean he no longer loves me? I can’t shake the feeling of insecurity, wondering if he still finds me attractive or desires me.