You make me think of a couple more things you should consider about all of this....
It does in fact sound like you can and want to love multiple people. Loving is easy, though; it's managing relationships that is hard. Very, very hard, sometimes. Do you think you can realistically manage more than one relationship? On what level(s)? Can you maintain more than one sexual relationship, and still be able to satisfy your monogamous partner, with your decreased libido? (I'm not saying you can or can't, or that it should even be a factor - I'm just saying it's something else to think about.) Do you have -time- for more than one relationship? Can you juggle two relationships with your current schedule? Three? Seven? On what level, and to what extent? For an extremely personalized example, I'm pretty sure I can manage one or two relationships, if both partners have at least one other partner in the picture or have a very strong independent streak and need a lot of alone time. I can add to that maybe two or three infrequent friends-plus-more "semi"-relationships - people that I'm not "dating", per se, but love and spend time with, maybe be sexual with, but on a very casual level. I've learned this through experience, though, and I don't know how to explain how to learn it for yourself, I'm afraid.
What will you do if you hit it off with the new guy, with your boyfriend's blessing, and suddenly find that your boyfriend is being neglected time-wise or sex-wise or otherwise, due entirely to the amount of time you spend with the new guy? Will you spend less time with the new guy? Will he resent you for it? Will you resent your boyfriend for it? Will you break up with the new guy? Would that be something you discussed with all involved first?
Just some food for thought.
And a big, important point that you probably are already aware of.... The libido thing. Are you happy/satisfied with where your libido is? If so, maybe just go with it. But if not, can you discuss with your doctor about the prescription(s) you're taking and how you can combat this (actually major) side effect? Or if there are other options?
Oh, and - considering the circumstances, I really do think you should talk to your boyfriend before discussing polyamory with the guy you're interested in. I recognize that he may be the best/easiest source of information right now, but.... It'd be pretty cruel to your boyfriend, I fear.... Think from his shoes: He knows something's up. Give him credit, he may even know WHAT is up, moreso than you think. You talk with new guy, discover that yes, you're polyamorous, and YES you want to do something about it, and OH YES you're totally into the new guy, and he's into you, and then you tell your boyfriend that you're interested in the new guy and want a polyamorous relationship, and oh, by the way, you've already talked long and hard with new guy, and he's soooooooo spot on about how polyamorous you are..... See how this could send your boyfriend into a spiral of villainizing the new guy, and being hurt for you talking with "The Other Guy" before even TELLING him?? Just a thought. Sincerely, I think you need to talk to your boyfriend WELL BEFORE even considering talking to the new guy - even if it IS just to try to understand polyamory better.
Your very best option would be to track down a poly-friendly therapist and talk it out with someone whose profession it is to help others understand themselves. If you find a therapist that you like, it will be the best money you ever spent. I DO agree that you need to talk to some "real" people, not just strangers on the internet. Strangers on the internet might be able to give you a view not biased by your own opinion, but friends actually KNOW you - and therapists are trained to professionally guide you in knowing YOURSELF.