Is It Okay to Still Miss your Ex sometimes?

My ex was my first boyfriend, not relationship, so he holds a really special place in my heart. I have my current boyfriend who I love with all of my heart and constantly communicate with him so our relationship can work out. But last night I had a dream about my ex and we were just like we were before we broke up and now I kinda miss him. I wouldn't break up with my boyfriend for him, but I just feel bad for even missing him in one way or another. The way we broke up was so sudden and rocky it kinda still hurts because I don't have that peace of mind like I did in my other relationships. I still have contact with him, I've asked my boyfriend if it was okay and show him our messages. But is it okay for me to feel this way? I feel guilty.