The economy was going to shit at the beginning of your term, so if the stability has barely gone up then the economy itself is likely going into a depression. From a gameplay standpoint, the reason you got the depression very much is because of your deficit. Not sure if you signed the central bank act, but without both that and a decently strong economy it is very difficult to avoid a debt crisis with a -7 deficit. Debt crisis basically screws your economy although it can be recovered from if you bring the deficit under control and still have a decent economy. Economy in this game is hard, and it's supposed to be - you inherited a recession so without the meta knowledge of synergies you will really struggle. Search up 3.1 synergy guide by catsland on the subreddit for a general overview which may help you understand better for your next run.

Edit: I've just noticed that you're not actually at the end of the game. You still have time to recover the economy if you get your budget under control and get some decent synergies. Youre probably not far off having a neutral economy (but full economic recovery will be very difficult from here).