Have namechanged for this as I'm a little 
I saw XP yesterday at one of our DCs Christmas parties. I just felt an unexpected surge of emotion when I saw him, so much so that I wanted to grab him. It was all very strange.
When we split up, our youngest was only one, we almost made it through that difficult time when DC are very little and the relationship is under such a lot of pressure, sleep deprivation etc. Almost. It was incredibly heartbreaking at the time. I think we both made mistakes, did things we regretted (not involving other people, just like saying not very nice things to each other/not supporting each other, that sort of thing).
Fast forward a few years and I have a new partner who is great with my DC. He has his own faults (don't we all!) and it's far from perfect, but it works and everyone rubs along.
I just don't know if I genuinely miss my ex or my mind is playing tricks on me, whether I'm being unfair to my new partner. I would never do anything or act on this, but somehow thought-crime is bad enough and making me feel incredibly guilty. Should I ease up on myself, or are my feelings wrong and unfair on my partner? I'm so confused. It's much more complicated, but the bare bones are there.
Thanks x