Congrats, having kids was the hardest thing I ever did. And it was REALLY hard, not that I'm a bad father but because kids pulled out all the things that were lingering with my spouse that were left unsaid but were there, simmering in the background. It may sound rough but the kids eventually put the nail in the coffin for my marriage.
On the brighter side of things kids help remind you what it was like being a kid, Christmas mornings, going and playing in the park, snuggling and watching a movie. Having a hard day at work and them there waiting for you by the door to give you a hug and remind you that no matter how shitty your day might have been, you're still the best thing in the world to them. Being a parent is awesome.
You get what you put into it, be there for them, even when sometimes it feels overwhelming, it will pay off in spades when it comes to building a lifelong relationship with them.