Urgent help

I suffer with agoraphobia so I’ve been putting off going to the dentist for the longest of times but it’s become unbearable. My top back right tooth randomly started crumbling, I’m now left with it looking like this. The toothache is awful it’s sometimes all along the whole top and bottom of the right side of my mouth. When I eat and food catches in the spot it is the worst pain. Due to be agoraphobic, does anyone have any idea what this could be / what treatment I would need just so I could be prepared about what’s going to happen. TIA❤️