General aviation instructor report a near miss and later a ground conflict with the same aircraft at ERV; a non-towered airport; during a training flight.

Narrative

On Day 0; between the hours of XA00-XB00; while conducting a traffic pattern lesson teaching a student pilot how to land; I (Aircraft X) encountered a hazardous pilot. While my student and I were on left base for runway 30; Aircraft Y made a call that he was going to takeoff runway 30. As I turned base to final I saw that Aircraft Y was stopped on the runway numbers to line up and wait while a different plane was taking off on runway 30. I made a call saying I was short final with the aircraft on the numbers in sight and would be conducting a go-around. While teaching my student how to go around; we side stepped to the left of the runway so that I could keep the aircraft in sight. I looked over to see Aircraft Y had taken off and was now no less than 200 ft away from me as we both climbed on the departure leg. I made several calls advising where I was in relation to Aircraft Y; but he proceeded to attempt a left crosswind turn into my path of travel. After more back and forth; Aircraft Y gained clarity with the situation and remained on a runway heading while I turned an early left crosswind. The pattern was busy; so we ended up having to follow a third plane in on a 2.5 mile final. I made all appropriate calls stating position and intention of doing a full stop for each leg of the pattern. As I turned extended left base; Aircraft Y followed very closely behind whereas I would have extended downwind for spacing. On final; I again said I would be a full stop. I was instructing my student through the landing; and we ended up touching down near the 1000 footers. I made a call saying I had touched down on runway 30 and would be rolling to the next available taxiway Foxtrot. Aircraft Y then called saying 'you better expedite that taxi; I'm on short final'. I advised Aircraft Y that he could go around as my student was learning how to taxi and could not expedite the roll safely. At that point; I turned to look out my rear window and saw that Aircraft Y had landed on runway 30 while I was not even halfway down the runway to exit. As I was rolling off the runway on foxtrot; I looked behind me again to see Aircraft Y taking off of runway 30 before I had even crossed over the hold short line. I taxied back to the hangar and finished debriefing my student. As I entered the FBO building; my coworkers all mentioned what happened; and of Aircraft Y trying to turn a left crosswind into me. Other coworkers who were also in the pattern said they heard everything over the radio.Afterwards; I went to preflight with my next student. As I was observing the preflight; Aircraft Y taxied over to me on the ramp; shut off his plane in the middle of the ramp; and walked over to me. As he was walking over to me; his child also got out of the aircraft and joined him in talking to me. The pilot asked why my comms weren't working and what was wrong. I explained that everyone else in the pattern heard my radio calls; so that wasn't the issue. I then told him that not only did he put a lot of lives in danger due to his mistake and again with his grossly negligent actions in the pattern; he was also setting a horrible example the impressionable child in his passenger seat. I ended the conversation to continue my lesson with my student. In summary; Aircraft Y made a mistake in taking off while I was doing a go around and led to an unsafe situation where I had to take immediate action to prevent a collision. After the accident; Aircraft Y then maliciously chose to land on a runway I was occupying with full knowledge of my location and my intentions. The hazardous attitudes displayed in his actions today are unacceptable and should be addressed before harm comes to any aviators.