Having a really difficult time accepting my 2.5yo daughter's "stepdad", how do I handle the resentment?

Long story short my ex and I had an unplanned pregnancy only a few months into dating. We tried to make it work, but couldn't. We split late last year and have a pretty cooperative and amicable coparenting arrangement. 50/50 split, no overnights for me yet because DD is still weaning and transitioning from cosleeping into her own bed but in the next few months she'll finally be able to stay over on my days.Recently my ex has started dating someone and it's getting serious, they're talking about moving in together. By all accounts he's a great guy, he is kind and intelligent and has a good stable job. My daughter likes him and though it's still only been a few months there's every indication that he would be a good role model for her and a good addition to her life. Both ex and myself come from broken homes and don't have much in the way of family, but he does. On paper it's a perfect arrangement and a good thing for my girl. He's overstepped a few times inadvertantly but backed off when it was pointed out. So what the problem, right?The problem is it's eating me up inside and just wrecking me emotionally. Because I don't have overnights yet and he's over there every day it means that strictly speaking this man sees my daughter more than I do. She's so young and I'm terrified that this will undermine her relationship with me and her perception of me as her father. When I see them play together, or when I'm forced to confront the reality that he sees her every day and I don't, I get this primal anger and sadness that I don't know how to process.I don't act on it and I've been respectful of him and have tried to make it a point to show him that as long as he puts DDs interests first we're cool. It doesn't make it hurt less, though. My girl is everything to me, and the thought of our relationship being diminished is driving me into a depression.What do I do? Has anyone been through this and come to a place of happiness and acceptance? What is your relationship like with your kid now?I know there isn't a real answer to this but I just want to know it gets better and that I won't lose my role as dad :( via /r/Parenting http://ift.tt/2u0gfFb