I don’t know what I’m feeling.

I just had my first intimate moment on the phone with a guy I’ve been seeing for a month. We haven’t been physically intimate yet. However immediately after, I felt guilty and I don’t understand why. My last relationship ended 6 months ago. That ex was my first official boyfriend and he was the only person I’ve introduced to my best friend before she suddenly passed away last year. That relationship did not end well and I was mad at him for a long time. For the guy I’m seeing now, I’m very happy with him. Our personalities match extremely well and I feel like he suits me better than my ex. But a part of me is struggling to move on from my ex. I have zero feelings for him, but because of I have memories with him with my best friend, moving on from that relationship feels like moving on from my best friend too. I don’t know how that’s possible but that’s how I truly feel. I hope someone can help me make sense out of this.