I come from a traumatic upbringing with no real family dynamic. One thing that kept me sane in my childhood (I'm 25 now) are my friends. But they would eventually ditch/abandon me in middle school which was a very bad experience that I still suffer from (social anxiety, bpd, depression, a lot of garbage). When I sleep I tend to have weird dreams. They involve friends/people from the past that I'm hanging around with. From what I remember I feel like an "outcast" or even "angry" in my dreams. I think it's not until the end when I have these feelings. Another set of dreams I have is that I'm almost in a completely different dimension. I'm me, but hanging around different people I've never met. I feel like I'm completely at home in these scenerios that I've never been to. It's almost when I wake up I'd rather stay in this world. It feels so real. I can understand the previous dream but the latter doesn't really make sense. Any ideas?

Consider the trauma of your upbringing, this otherworld is an ideal plane you long to escape to in your mind away from the trauma.

This otherworld, is it a figment of my mind or is there more to it? Just an escapism or an actual reality? (I'm just starting to read up on dreams and don't know if they relate to anything spiritual or if it's just a mental matter).

I think it can be both. Spirituality is a broad term. Going to other dimensions in dreams can be a form of spirituality. Does it feel spiritual to you? Then it is. I've had similar dreams where I've met beings that I could only describe as having other-worldly qualities and I felt like I was in the presence of something sacred.