First al all, welcome to the Nexus breathe.
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Yes, the feeling of 'losing ones own mind' or 'losing that sense of I' is a very strong hallmark of this experience. I think most here (including the vets) are somewhat used to the notion of obliterating their sense of self completely.
When you decided to "do dmt one night on a whim outa boredom", well.......dmt did you. You always have to have the utmost respect for this experience and try to prepare yourself beforehand, mentally/physically/setting. Doing this can help throw the cards in your favor.
You said that you couldn't let go of your sense of "I", you were scared, plus the overwhelming intensity that it was putting on/ This right here...you just answered your own post per say. Learn to meditate, still your thought stream, learn to LET GO.
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I guarantee that the reason for your rough ride is because you were consciously resisting the inevitable conclusion, that you, have to cut the cord, at some point. Like a little boat attached to the dock, whilst the infinitly mass of stormy seas ahead, at some point you have to cut that rope and just give in.
And there's no such thing to me as "bad" experiences, just misunderstood and misguided experiences. You weren't ready for the intensity that the experience can bring forth, you resisted...resisted your own death, and therefore the experience compounded on your uncertainty and fear/anxiety...jet fuel for the fire. Let me tell you, dmt will always throw a curveball, and can take you through a never-ending cascade of experience, it can always get crazier, it can always get more intense. There's no end.
Take some time, think about the experience, integrate, write, sing, make art, exercise. As i said above, learn to still your thought stream to where you can go into the dmt experience with minimal to no thoughts beforehand. This all can make worlds of difference.
Just remember.. tat tvam asi.