Looking for a little advice and support

[azguy]

Sounds like you're trying to set boundaries (usually helpful), but also conveying unhappiness (not helpful).

"I can't continue to put my work and life secondary to your horse life.
I'm beginning to realize that we need to figure out how you are going to do this without me in the picture. I can't just stop what I'm doing. I'm sorry "

I'm not sure how you think this comes across. To me it sounds like a threat to withdraw. Might it be more helpful to say something like "I want to help but need a clearer schedule to be able to coordinate this with work. I'm asking you to provide me x amount of notice." Then stick to whatever agreement you think you can make.

"This is something you need to start figuring out anyways assuming we divorce. I think you know that though."

Why are you bringing up divorce? Sounds like you have one foot out of the relationship when you say this.

"If I've learned one thing with your new world is that it usually doesn't. "

You sound bitter here. Does it really need to be said?

Overall, I like that you're trying to offer her support and coordination. Offer her what you can in the spirit of kindness. Be clear to her when you cannot, without blaming her for it (if it's last minute, you can't help, but you don't need to point out it's her fault, it's just too bad it worked out that way.) Rooting for you. Maybe some more experienced members can have better insight.