Seeking advise how to end a FWB relationship

(The content may be NSFW) I just want to share this experience I recently had. Also, I am hoping to get some advice or tips on how to deal with my current situation. So I met a guy on Tinder and we hit it off right away. He's about 6 years older and a few inches taller. I admit that I was a bit of a rush wanting to explore my sexuality. After more than a couple of weeks of texting, we began to become intimate and more frequently than I expected. I loved every part of it and I can tell he does too. For about a month, we have sex whenever we can. You can imagine a horny top and bottom going at it like there's no tomorrow. I know that he is not completely interested having a relationship with another guy. That is completely okay with me. Given that he admitted that he is still attracted to women. He is obviously straight-acting as he said himself. I can safely assume he is bisexual. Recently, I opened Tinder to turn off my "Show me on Tinder," this is when I found out he has unmatched me. Either that, or he deleted his Tinder account. On that same day, we had sex and I didn't want to ask him regarding the "un-matching" as I didn't want to be so forward and creepy. Being the resourceful me, I did find out he unmatched me because he was still on Tinder and have changed his profile description. He now claims he is a "cub/puppy" (younger men that date older women) who dated cougars for more than 5 years. In addition, he added a sentence to express his interest in dating women his age. Ofcourse I was completely shocked at first but had to swallow it all as I know myself I was indeed just hoeing myself out. The thing is, I liked the friends with benefits situation and did not expect any infatuation between us, all cool. However, knowing that I sucked and got penetrated by a dick that previously been inside a cougars vagina is unsettling me (No offense to the cougar community). To add to this, a very close friend of mine who I've been telling stories has seen a craigslist add from the same guy with an add wanting to participate in a threesome with a straight couple. We had already set the dates when I will be coming over. Soon, he will text me what time will I be coming over and I just don't know how to end a FWB relationship. Any advice on what should I say to let him know I no longer want to be his hoe without being too upfront regarding his attraction towards cougars and other fetishes? (He doesn't know I know of this side of him). P.S. I do really like the guy intimately in bed, although he has that "Boy Next Door" movie character in him.