I gave my boss an ultimatum

For the past 2 years, morale within my department has been at an all-time low. I want to spare the details, but everyone on my team (including myself) has tried to discuss our dissatisfactions to the general manager, but nothing has come from these discussions. I am a senior member on the team and feel like my concerns are generally taken more seriously, so I often speak up on behalf of the team in hopes that things will get better for us. We are often lied to by our department manager (such as about promotions or pay raises) and no one on the team takes him seriously. For example, one team member was given a promotion back in October, but was told she would not get a pay increase to go along with it until January. Well it's January, and she has not seen a pay increase, but she has been expected to take on additional responsibilities. Another team member was recently hired and was told upon being hired that she would see a pay raise after 3 months. That didn't happen. Many people on the team have had it with the false promises, but unfortunately we have done everything in our power to try and have oir concerns addressed, to no avail.

My main concern has not necessarily been about the pay, but about my job responsibilities. I have been doing the same job for 4 years and have been growing exhausted from the monotony of it. I expressed to my manager 6 months ago that I was feeling burnt out and that I want to be expanding my skills and learning new roles within the company. I was promised that I would have the opportunity to do so.

I just had my yearly performance review last week and my heart fell into the pit of my stomach as my boss told me what his plans are for me this year--more work on my plate doing the same job I have asked him to step away from. And of course no pay increase to incentivize the extra workload.

I thought it over and let that feeling sit in my stomach before I ended up writing an email to my boss telling him that I felt my concerns had fallen on deaf ears. I explained again that I have been burnt out and that I no longer feel it is in my best interest for my wellbeing to stay in my role. I told him that I really want to be expanding my skills and can't do that within my current role (I've mastered it), and I told him that I'd like to have a discussion about whether or not there is a better fit for me within the company. I pulled the trigger by saying "if there isn't, I will unfortunately have to resign."

Since I pressed 'send' on the email, I've been freaking out. My job pays very well and has great benefits and culture, but it is draining my soul. I don't have anything else lined up and I'm scared of what will come once I meet with him to talk about it this week. I hate having to choose between financial security and mental stability. I have of course started job searching, but things are tough in my area, and I don't expect to find anything with better pay or benefits. I'm just in a dead-end job right now and not getting any younger. I know I have to be prepared to walk away if my manager doesn't have a better plan for me, just because I gave an ultimatum and would need to keep my word. My coworker insists that they would never fire me because I'm way too valuable to the company, and honestly I've never seen anyone get fired, even if they consistently miss work, etc. The company culture is like "who cares, do whatever you want" with no repercussions for anything. I am consistently a top performer and can't imagine that they'd fire me either, but if my ultimatum doesn't go my way, would it be smarter for me to "quiet quit" than to simply walk away without another job lined up yet? Other people on the team get away with stealing company time. Some take entire days off while on the clock because our boss doesn't notice when people aren't working anyway. I'm thinking of doing the same until I find something else, that way at least I still have a paycheck coming in, I won't be burning myself out, and I could potentially collect unemployment if they do fire me. What does FDS think about quiet-quitting?