What happened?

Hello my name is Gaio. I need help to understand what happen to me! In 2012 I start meditating, at the beginning it wasn't easy but in no time I was able to clear my mind. I was meditating for around a month and a half when something strange and scary happen. So I seat down in my normal place to meditate and started. I close my eyes clear my mind. That's when I start feeling something different, I wasn't in my room anymore. See if I can explain, I was floating in a dark place nothing around me, just darkness and something like a triangular portal, I wanted to walk trough it, I tried to. As soon as put my head trough it I saw 3 creatures coming to me and felt really bad energies. At this moment i quickly open my eyes. My body was shaking I feel really bad afterwards. After this I can't meditate. It's now been almost 4 years. I try and try but can't clear my mind. I have my theories but Does anyone experience the same? What was that?

Have a great day Gaio