Job Offer without job description

Okay, outsiders perspective:

You said you wanted to leave. You said you had other offers. They called your bluff. You folded. You did not leave.

You have zero leverage left.

It's time to actually go look for that better offer you claimed you already had.

Past behavior indicates future behavior

If this company has already lied to you multiple times in the past, and strung you along with false promises, why do you think they will suddenly stop now?

There are phrases like "Fool me once shame on you, fool me twice shame on me." This company has been repeatedly making a fool of you, and will continue to do so until either the people causing the problems are gone or you find a better employer. So unless you have some magical way of fixing the leadership of this company that only leaves one viable solution: Find a new job.

With that said, it is far better to line up a new job before quitting. Once you have that new job, then give the minimum notice you are legally required to give and ignore any counter offer they make, knowing that any promise they make is not worth anything.