Compartmentalize it or find someway to use it constructively.
I get pretty dark myself but i mostly apply it towards art I'd like to make--like some stanley kubrick morbid depictions of reality; or venting via music. Be careful though, because this can become habitual and may have some effect on your brain chemistry non-temporarily.
It can lead to a lot of guilt or self doubt. Just because you feel dark doesn't mean your a bad person, as some self-awareness and acknowledgement in my opinion, is better than being completely devoid of any empathy or consideration of ones actions--like tobacco execs or something.
Maybe cut back on the weed too as it can cause unrealistic perception.
If you feel guilty about it try to keep it light for a while.