I emailed the guy who handled all the deposit checks during that time and he said everyone in the house paid $643 each and that Mr. K paid him that much also. He also had the posted date of the amount in his bank records. He unfortunately couldn't get an image of the check since it was too far back.
Earlier today I confronted Mr. K with an image of the check I wrote to him and email transcripts between me and the deposit guy. I never yelled, accused him, or rose my voice. I said that there were two different sides saying two different things and that I was caught in the middle of it, and I want to get out of it. I got him to check his bank records online while I was at his house and he said that he indeed sees that he paid $643 to the deposit guy. He stated that he realized that he has to pay me $137 and that he would have to pay the money in two different checks. He stated that he didn't have any malicious intent and really thought the deposit was 1.5x rent. He said he would pay me the first increment by a certain date we agreed on, and that he would pay me the rest (or next increment) a few weeks later.
All in all I'm pleased since I got him to realize and confirm that he has to pay me $137. However, nothing is certain until i get all the money