Forgot to mention that if I were you I would not acknowledge nor mention the note. If he wants to move out he will have to bring it up again in person, though some are not able to do that and will slip away without discussion. Regardless I would not discus it. Prepare for if it happens, especially regarding financially protecting yourself
R 25 years M 14 years S11 & S13 Working on it alone since Oct 2014 M in trouble a lot earlier (~2 years) Feb 2016. 1st R chat in a yr. Next R chat Aug'17 Still together