Genuinely if youve moved out its probably a really good thing. Though its heartbreaking honestly its better at this stage befote you start losing a grip on reality. It sounds like you are doing a really good job of thinking rationally which is amazing. Him “getting worse” because you have left is a lie that he will either tell you or you will tell yourself because he was doing this long before you came into his life and he was doing it during your “happiest” moments together. So dont be manipulated into trying to rescue him. Initially my boyfriend told me he didnt need professional help, that if I would just help him then he would be able to recover but it was a huge mistake because all of the pressure I took onto myself and every time he used and lied it became a personal faliure. You sound like a very strong person and you deserve the best in life. Think carefully about what you want long term and how you feel you will be able to cope if the situation was the same in 6 months or a year.
Hugs