Sounds like you have come to a conclusion. You seem to show sensible judgement and will choose well even if the choices are difficult.
Don't be afraid of choosing. We choose all day long, hon.
What to eat for breakfast? What clothes to wear today? Where to park the car?
Just that some choices are small and others are big. Some consequences are felt as small things and others as big things. But ALL choices come with consequences. Even choosing not to choose -- that is a choice. Time will march on and here comes the consequences of passive selection.
Could keep working to get out from being so dependent on your fiancee. Maybe apply for work elsewhere with improved pay. Or even same pay but better emotionally/psychologically so she is not also your boss.
But def don't get legally wed if your thoughts are running in that direction right now.
Again, better a SUCCESSFUL engagement that helps you both to realize you are not compatible for marriage. Than a failed marriage stemming from a poorly executed Engagement Time that was to rushy or not talking deeply enough.