Is talking about quitting to your supervisor a point of no return?
Talking about quitting with your supervisor (or someone else in your supervisory committee or department) is not a point of no return. In fact, it can be a turning point.

PhD students all go through ups and downs and part of the job of the supervisor, and others in the department and university (head of department, counsellors, etc) is to help you get through the rough patches. 

If you do not talk about it and things get so bad that you actually quit, then it may be a point of no return.

Full disclosure: I quit my PhD. The first my supervisor heard of it was the day I quit. Luckily, someone else gave me another chance a few years later.