I've been dating a guy for two months and he wants to sleep with someone else.

We've been dating for two month, not exclusive, but a few weeks ago we agreed we'd be jealous if we slept with someone else. This morning he started a convo with me starting with "I walk to talk to you about something but I think you'll leave me for it" basically he wants to sleep with a friend thats coming in from out of town for a week (who he said he has an emotional connection with, not just physical attraction) and since we're not "exclusive" it should be ok. I pretended all morning it was fine but it's really not and the more the thoughts fester the more sad I am. What the actual fuck should I do and are my feelings fair? He just had me bring extra clothes and toiletries to his house so I can sleep over before work days. I sent him a text for us to talk it out in the morning since I'm having obvious second thoughts but I really thought we were moving forward but this feels like a slap in the fucking face and I'm not sure of the most healthy way to approach it, I don't want to lose him because its making me sad, but I don't want him to go through with it. Like fuck men? Or am I being bloody dramatic? He's my first "boyfriend" and hes had a few long term boyfriends in the past, we're 26 and 27.. Any advice I would love, honest. Thanks for your time guys.