Anyone who tries to take sports betting "professionally / semi-professionally" has experienced this, so don't be disenchanted. The important thing is to learn from your experience so that you don't do it again. You already know what you need to do to correct this and avoid it in the future.
I recently had a run of losses that depleted most of my winnings from a 1-2 month period, and the below is mostly what I did to put myself back in a competitive frame of mind. The goal is long-term profits, so for me, correcting my losing streak was more about protecting my yearly winnings from an 'incorrect' mental attitude that was temporarily looking for opportunities that weren't really there. I always try to be mindful that I'm the weakest link in my system.
I want to suggest three things to you that helped me get out of my rut:
Take a month off. Give your brain a chance to get over the error and loss of cash and reboot a little. Do something else for a while and get back to a 'neutral' headspace. Sounds like you're basically just beating yourself up for fucking up and losing a lot of money - get over this, because as you say, if you did it once then you actually made a lot of correct bets (and therefore are good enough do it again). Trust your form / long-term trend.
Start your bankroll again from scratch, and only bet with money you can afford to never see again. De-risk yourself from the emotional impact of a big loss by betting small and having to play smart to protect your new (tiny) bankroll. Betting $1 is a good suggestion to get back into it - I have a friend who stakes less than $5 each time, and his only goal is just to pay for his work lunches each week. Maybe you could set yourself a small target like this to work towards and keep your profit target focused.
Establish a max bet limit based upon a share of your bankroll. Accept the frustration that results from having this system limit your ability to place large bets on a single game, because you now know what happens when you get it wrong. It might be less profitable and less fun, but you won't ever lose large chunks of money if you're betting with 1-3% of your bankroll and it will bring structure and discipline to your approach. I use a 1% / 2.5% / 5% system (scaling according to confidence), but also with a financial control that only a maximum of 50% of the days beginning bankroll can be staked - basically a protection to ensure that I will always have some bankroll to bet with tomorrow and the day after.
These things helped me get back to it - maybe they will help you too. Good luck!