Are you feeling like you think you look like you're a slacker or not good enough at your job bc someone else is taking this monstrosity of a project over? I know that when in my professional life I have tried to set limits (I tend to say yes to everything, get swamped, overwhelmed and nearly lose my mind) I feel like those I'm saying "hey I think I might need someone else to assist with this" to will inevitably think that I am incompetent, a slacker, taking the easy way out.... you name it, I think it.
I imagine a lot of us (I know that my issues with how I interact with AH stem from my FOO) grew up in less than healthy homes where limit setting wasn't encouraged or taught or seen as something positive. Asking for help and knowing one's limits (at least in my FOO) was seen as being a failure and weak...
So, I wonder if any of this kind of thinking might be going on for you with this situation?