Trying to make someone jealous is a very normal thing to do when you like them. But what he did was going a bit too far. Asking someone else out in front of you crossed the line because now it directly involves the feelings of another person. If he just wanted you to be jealous, he should've just flirted with other girls in front of you. No harm can really be done there because if he truly did like you, he doesn't have to give any explanation to the girls he flirted with. But since he asked out that girl, he'll have to explain to her that asking her out was just a fluke if it turns out that he does like you. Either that or he'll randomly dump her and then start dating you which makes him a jerk since he wasn't considerate of the other girl's feelings.
So whether he likes you or not, this guy isn't worth it. If he doesn't like you, then that whole thing with him asking out that girl shouldn't mean anything to you anymore. But if it turned out that he did like you, him crossing the line should prove that he's an immature guy who doesn't really know the true meaning of consequences nor is he a considerate person. It just makes him look like an inconsiderate, impulsive guy who could literally do something pretty drastic without anyone seeing it coming and without thinking of the people involved. It may seem fun to have a guy like that as a boyfriend but in practice, it's not fun. He may randomly break up with you all of sudden and he won't even bother to tell you why. When that happens, it's no longer fun. It's actually pretty darn painful.
That's why just forget about this guy. I know it's going to be hard since you like him but he's honestly not worth your time and energy. If a guy wants to be with you, he should at least have some class and not do something so ridiculous and inconsiderate. Yeah, people can be stupid sometimes but, to put things harshly, do you really want someone who is that stupid?