Realizing your dreaming

I have these types of dreams alot, the last one that I recall (not necessarily the last one I had) was about my ex-roommate (really bad situation). In the dream the old room mate had moved into our new place and I kept asking my husband why he was there. I started yelling at the guy to get out of my house and then realized it was a dream and said "Wait, this is a dream, you don't live with us anymore, this would never happen." I think I had it because I was still hanging on to the anger that I let that situation make me feel, it was time to let it go but some part of me didn't know it until I told myself.