It's hard to let go sometimes. But sometimes you have to. Especially if the boss told you to.
In your example, once you handed off the project it was no longer yours but your co-workers. Especially from your co-workers perspective. When you jump back into the project uninvited it is natural the co-worker feels threatened.
What to do about it? First try to see it from the other persons perspective, coworker, boss, customer or whoever. Second, do you have interests outside of work? That involve people? If yes practice your social skills. Listen, observe and always think before talking.
Don't feel too bad. We all "lose it" from time to time. My solution is to go for a walk when I lose my temper. Even if you can't do it at work you can after. It's amazing how much good a half hours walk can do!
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