I feel like the dumbest guy on earth and I don't know if I have strength to keep going
Could you tell me more about what makes you feel like you don't have enough strength?
I've been working on the same shit for 3 years and nothing gets finished
It's understandable that you may lose hope after trying for so long. However, you should not talk down to yourself. Instead, try using words of affirmation to encourge yourself to persevere.
I'm going to give myself a break and take my bitch to a movie.
You shouldn't talk down about yourself, or your girlfriend for that matter who I am sure is not a bitch. You seem to have low self-esteem, so you should work on that with your downtime and then come back stronger.