So we’ve established:

• He’s perfectly fine with lying to you
• he’s friends with dishonest cheaters
• he wasn’t just wing manning, THEY were going to meet girl*s (plural)
• he went back to her place… makes me wonder who was wing manning who

Your bf is cheating on you, or he’s enabling others to do so, at the very minimum his actions are extremely inappropriate and 100% of questionable moral character. If you think that doesn’t matter, I mean that’s the difference between people who cheat and people who don’t