He's cheating on you. He doesn't value you or respect you. If he did, he wouldn't be chatting with any woman, and he wouldn't hide that fact that he is chatting with other women from you. The fact that he hid it from you, then deflected with a lie, "she's ugly," tells me he's manipulating you, so that he can have his cake (you) and eat it too (flirt with women via text and god knows what else with them, behind your back).

The fact that he deflected again, and shamed you into feeling guilty for looking on his cellphone when you two agreed that you both could do that, shows me again, that he doesn't respect your feelings at all. He doesn't sound like a good guy at all.

Ask yourself, do you want to be living with a man who makes you walk on egg shells when he misbehaves, then blames you when you point out his bad behavior to him? He sounds very immature.