Welcome, M_F_M!
How much have you talked to your wife about this? Is she already on-board, or do you need to negotiate this first? There's a fun movie called
Young People Fucking, it would be rated R if it were released in the US (it wasn't). One of the couples in the movie successfully tries pegging. If you need a gentle way to introduce the topic, that might be it.
Has she already played with your ass? It would probably be best to broach that level of intimacy before you purchase a toy.
Finally, a toy that stimulates her as she fucks you may not be the best idea at the beginning. I understand that it takes quite a bit of coordination to figure out the hip thrusting rhythm, and if she's being distracted by a vibrator, it may be too much to deal with. Perhaps that is something to work up to.
Finally, regarding teasing: everyone has an asshole. Liking anal penetration doesn't make you gay. Wanting to have sex with men makes you gay.