<human>: About a year ago I left my boyfriend of 10 years. It was easily the hardest decision I've ever made, but ultimately I do believe we're not right for each other as a couple. However, I continue to seriously mourn the loss of my best friend. 

We were friends before we dated, were in a relationship from high school into college, and then lived together after for several years. (There was a gap for a bit, if you're doing the math.) It makes me so sad that he is not the right person for me, because to find a better romantic partner I needed to lose him as a friend. And we're idiots for taking so long to figure out that it didn't work. He won't speak to me at all. 

I'm an emotional person (though I hide it), and I sometimes seem to be more intensely affected by things like loss than other people. I'm worried about how this loss is going to affect my future relationships. I have started dating and to be honest, it's weird. It's one thing to tell a new boyfriend that I seem sad today because I'm missing my mom who died when I was a kid. It's another thing to tell him that I'm sad today because I'm missing my ex-boyfriend. But the alternatives to being honest seem to be to (a) lie about my mood, or (b) lie about the reason for my mood. I know myself, and I'm never going to stop missing him, and occasionally I will need a moment to cry or some time to myself to think about it. I don't think that's wrong considering what an important person he was to me.

I'm looking for advice from people who have ended very long relationships, especially if it didn't end for some explosively terrible reason (abuse, cheating, etc.). Have your partners in new relationships been understanding that missing your ex doesn't mean you wish you were still with them? Do you just not mention it?

Give me a shortened version of the text
<bot>: I'll always miss my ex-boyfriend and this will sometimes make me sad. How much should I share about this in future relationships?