Well, telling someone about being an AB for the first time can run a gamut of emotions, from insanely awkward, to tense, to relaxing and quite pleasant. Your personal reaction usually depends on who it is you are telling, how comfortable you are with your AB side yourself and how long you have known this particular person.
I have told numerous people, friends and romantic partners mostly about my AB side and every time my reaction was a little different whilst their reactions were largely the same.
With the first person I told, my very best friend from high school, I was very nervous and anxious, stumbling over my words a bit, sweating, my friend could tell too. I managed to tell him and he said that it was an interesting past time for sure, but that it wasn't nearly as weird as he thought it would be based on my demeanour and he said that "We've been friends for so long, this doesn't change my opinion of you, just don't go wearing diapers around me". After that experience everyone else I told was a little different, with girlfriends, telling them was a very uplifting feeling, especially when they accepted that side of me, with other friends it was a mixture of nerves and elation. Most everyone I told was accepting in some way, hence why I said their reactions were all pretty even keel.
Over time, some of my friend's attitudes regarding this changed. All my friend's reactions were positive, but they became more comfortable and accepting of this side of myself as time went on. My friend from high school who told me not to go wearing diapers around him, is now fine with me wearing in his presence so long as I diaper up discretely around him. A female friend that I met at University over the last few years, she went from accepting it, but seldom talking about it to embracing it, she now teases me about it playfully from time to time and she even gave me some of her kid's old baby toys.
The more you tell people, the more comfortable you'll become with this side of yourself and the more prepared you'll be when you tell someone again in the future. From personal experience though, your personal reaction will always vary depending on the circumstances and the reaction of others will usually be pretty standard one way or the other, they'll either accept it or they won't. If they accept it, their attitudes may change, but they'll usually change for the even-better as in your friends will become even more accepting over time. I hope this helps