OP, when you look back and read this thread, you will wonder why you couldn't hear what was being said to you,
You have left it a little late to get your daughter use to her other parent, I suggest you use the time left to do so, not just for your sake but for her, and for your partner,
he can do it, just as well as you can, you just have to let it happen, does it worry you that he may be able to, and somehow that will make you 'redundant"? You seem to be holding on very tight.
It will do all of you the world of good,
Go away for a night this weekend,don't make a fuss, just go, no build ups, of big goodbyes, and no going daft when you get back, be matter or fact about it, and then do it again in a few days time, keep doing it, and then it won't be a stressful event for anyone, you have a few weeks left to get this going, I would grab every chance you can.
if you do, everyone will be a lot calmer when the real event happens.