Sounds EXACTLY like how I introduced my girl to being shared/used by additional men. We also confessed our kinks to each other after being together for a while; and lucky me (us) our sexual fantasies lined up!
I would NOT recommend using Tinder/Bumble, but instead use Fetlife. It's a social media platform that's been around since 2008 and is massive. The best part is you can see how much experience others have that your interacting with, see images they've uploaded, chat in forums about kinks, set up meet n greets, dates, or make plans to meet others at adult swingers clubs, etc.
I'd also suggest making the location of your first meetup be out of town, but not too far. You don't want to run into people that know you in your "vanilla" life, nor do you want to have a negative experience (it does happen) and be so far away from home, or spend too much money travelling really far to just have a mediocre experience.
Be straight forward and up front about what you two are seeking. Come up with a list of hard and soft limits, safe words, etc. Make it clear that at ANY time, you or she can call off any meetup if you're uncomfortable or feel the limits have been violated.
Also, don't settle. You'll find someone that lines up with your kinks, just be patient.