It's been a year since I started dating my first (and only) boyfriend.
I was 16, and it was a very difficult break up for me as he made my life difficult afterward, even though he dumped me.

However I thought I had really been over it for a little while. I just started having dreams almost every night about him. Weird. Most of them are eerie, scary, or strange.

This is the most recent one, which I remember the best:
I was killing people (guards?) and went to inform another guard the rest were dead. I made reference to the boot shape imprinted on one. I revealed to the guard the exact details of the boot- describing the tall black horseback-riding boots I was wearing, before killing him as he realized it was me.
I was leaving (or looking for someone?) when I was on the first few stairs of a light blue railed staircase (the rest of the building was white)
My ex, and a man, were at the top. I began speaking to them, I think telling them what I'd done. My ex's eyes were remaining hidden under his hair for most of this "scene". I came to the top, showing off (I think) and told them how my boots were silent.
Suddenly my ex was wearing a "Darker Than Black" animes main characters outfit, including a whip.
We were in a basement/garage or something, which was made of an orangey stone. The one entire end was open, like a garage, and my ex disappeared behind a corner. I found a way to peek and see where he was, when I turned to whip me
This scene was short, it jumped straight to a beach scene. It was me and my friends hanging out with my ex, with very slight alterations to him, sitting in a circle a few meters away from my "real" ex and all of his friends.

That's all I clearly and 100% recall.... Help?

Thank you

Has it been almost exactly a year?

If so, maybe there is something about the time of year that reminds you of when you met, which is why you are dreaming about him now.

Or something else in your life could be happening that brings up memories of him or of other things that were happening in your life when you were with him.

Killing people in your dream could be an expression of anger. Killing guards - could you be angry at yourself for "letting your guard down" with him?

The boot imprint makes me think of being "walked all over"

Do you feel like your ex may have used you or taken advantage of you?

Could your ex's eyes being hidden and him changing appearance have to do with your feeling that he wasn't being honest with you?

Whipping yourself could also be an expression of anger.

A beach is a place where you enjoy yourself and relax but your ex is on the beach with you so that could be a sign of conflicting feelings.