I think this incident is definitely cause for concern. You say he wouldn't hurt you, but having your head held down while he shoves a sock into your nose and mouth is a physical assault. He says he won't hurt you, but he already has, and that's the reason you're in group to begin with.

You said he is both "physically and sexually abusive", which means there's every reason to believe the violence will escalate. Being hit isn't the definition of domestic abuse, and often the violence slowly escalates to being hit. This incident sounds like an escalation.

The situation is serious. It's difficult to see that when you've been systematically abused and degraded, made to distrust your judgment, having your personal boundaries violated under the threat of more violence. This could explain why your emotions are dampened and empty. Listen to the people around you who have been in your shoes. We want you alive and well, cherished and safe, which is everything you deserve.