I'm glad that you told Anne. Whatever happens with Anne, or doesn't happen, open and honest is definitely the way to go about it.
But now suddenly she's busy and unavailable to spend time which could mean one of two things: the obvious straight-forward surface meaning, or that my fears have been confirmed. Who wants to be with a guy who's still figuring out his primary relationship... the timing just effing sucks.
Well... she could genuinely be busy. She could genuinely be concerned about your marriage being early poly. The other alternative is that she could be feeling your excitement and the volume of it may be overwhelming, regardless of poly. I'm not saying that to freak you out - it may not be true. But hearing the way you've talked, and knowing what I know about early poly situations, I know that we are all capable of grasping this fantastic new person who seems to tick all of our boxes and drive us wild... and sometimes, this can put people off. It's time to take a deep breath, my friend, and start approaching the poly situation with reservation, patience, grounding and realistic expectations. Completely enjoy the crush you have on her, but keep your dreams in check.
Take a look through your phone and if you see that you've been the one to get in touch first at least twice in a row, give her some space. If your texts highlight balance and equal interest, carry on as you are, but don't panic!
As for Leigh...
It's all about timing, my friend. Leigh will be feeling extremely vulnerable right now. She's trying to be very brave. She's likely extremely scared, and doubting herself. From her text, it looks like she really needed the intimacy with you. The following morning can be a continuation of the intimacy. It's usually the morning glow moment. Our hearts and emotions are vulnerable in the morning, because we are just coming back down to the reality of the normal day. To spend a night bonding and experiencing closeness, only to wake up and be reminded of your attraction to someone else, it's going to rip that closeness away from her.
Something that can work is to actually have a set time each day that you talk about poly. It doesn't have to be every single day - it could be every other day, or once a week. Ask her what time of the day would be good for her. It really might be a good technique. It allows you two to carry on as you are, without ignoring the poly issue, but without engulfing your relationship in it. The more loved she feels; the more one-on-one attention you give her; the more her trust will rebuild. And for the love of God, whatever you do, don't go mentioning Anne every 5 seconds, hmm?
And now I feel like I've lost them both. How the hell does a person juggle two vulnerable relationships like this???? I want them both in my life, but that's not 100% up to me and never was. Feeling lost.
It's going to be ok. If Anne leaves, it's not a good fit. If Leigh leaves, it's not a good fit. However, with talking, patience, and communication, it is entirely possibly to have what you want.
The first question to ask yourself is how committed you are to Leigh. If you do want to be poly, would you be willing to pursue this even if it meant losing Leigh? If not, she has to be your priority. If that means slowing it right down or even losing or holding off on Anne for now, so be it. (I'm not asking whether you love Leigh - I literally mean, if you had to choose between Leigh and polyamory, which would you choose? The answer will tell you what your priority is. Either answer is perfectly ok.)
So then, if you do decide that, at least for now, Leigh is your priority, focus on that. Let Anne be what it will be. If it's meant to be, it will be. Offer to take your wife out for polyamory-free conversational dinner and spend one on one time with her this weekend. Also plan to have a long talk about polyamory the following afternoon or evening. Both things need attention. Start slowly. Start figuring out your boundaries, her boundaries, and start laying things out. First port of call is to ask her how she'd like to communicate about polyamory. Go from there. Just open the doors of communication and let things start to flow. Read, read and read some more. Then come back and ask more questions