Breakthrough experience, but also worried and scared

I was in the middle of a session with my therapist and he suggested that we do a short guided meditation, nothing unusual really.

He was guiding me, and after only 3 or 4 breathes, I had to open my eyes to interrupt him since I had a very significant experience.. I said "Wow something just happened. It's like my mind was floating above my head for so long, and suddenly now I felt it go right back into my head. Suddenly, all I saw were my closed eye lids and everything got quiet".

That's how I explained it at the time. He looked amazed and said, I think you "returned home". That's a good way to put it.. It felt almost like a displaced shoulder that popped back into place.

I went on, trying to explain my current state of mind to him. I've seen him for the past 2 years, I've suffered from anxiety and constant overthinking and self esteem issues.

I said to him "It's weird, everything looks different to me. This whole room... You look different.. I am very aware of your shape all of a sudden. Like, you only look like a shape of yourself, but it's like I don't understand fully what you are anymore. It like I don't have any labels for anything in this room, so everything feels very alien. I can understand the shapes of the objects and obviously I'm speaking to you and I can tell you're my therapist, but you're not labeled as *name* or therapist or anything". I was scared now. At first it felt exciting because it was a breakthrough feeling, but it felt so alien that I soon started to doubt my sanity and felt scared of losing my grip of reality.

He offered me to go for a walk in nature for the rest of the session as he calmed me down. It ended up being the most amazing walk through the woods and fields. To elaborate, the experience felt like a dream and unreal almost. It was strange. People were smiling at me and making eye contact in a friendly way, I felt very connected and at peace, no social anxiety at all. The sunlight shining on me made me uncontrollably smile for myself. There was basically no inner dialogue in my head. My ego was diminished, but not dead. More like it was taking a backseat and watching the experience instead of running it.

But it went back and forth from feeling alien and scary, to euphoric feeling and beauty.

Anyway, this experience lasted for about 3 hours. I thought maybe it was a one time experience because the next day I woke up with my regular racing thoughts. But around night, same thing happened again and it felt amazing once again for about 2-3 hours.

3rd day in a row today, I get the same exact experience again for about 2 hours. However, today it was scary and very alien so I got worried of losing my grip of reality. After a few minutes I calmed down but it almost lead to a panic attack as my surroundings looked more and more strange.

Every time this happens, it's the same thing. I have no inner dialogue, I feel very present but everything seems alien which can be scary. What the hell is going on?

Can you guys relate to this? I know I'm not enlightened of course, and certainly don't want to be either. I'm not even actively meditating for gods sake. But I'm scared of mentally derailing when this happens. My goals were just to have a reasonable amount of anxiety and overthink less, but certainly don't want ego death or anything like that.

My best guess about is, my brain is letting go. I walk around in constant thought and anxiety, so much that it feels "off" when I'm thinking as I usually do. This leads to a fear. A fear of the absence of anxiety. I guess this makes me doubt my sanity, which takes me down a rabbit hole of paranoia at times.

Because that's how I've survived for the past 25 years, and I probably believe I need to be anxious or else things might go wrong. Let me know your thoughts, you can ask me anything.