Bf is really trying me

Hi. I going to try my best to make this short. So I’ve been with my guy for some months now. He is a dope person well so I thought. We were in a movie theater and his phone rings. For some reason I assume he saw I noticed but I didn’t say anything. He hugs up under me and the phone is still ringing through his Apple Watch and I see a woman’s name. I don’t say anything I continue on with the movie. So fast forward the movie is over and we get in the car I ask him who that was. He tells me a “old coworker” I leave it alone. He kind of over explained himself when telling me going into detail after detail. Two days later something not sitting right with me. I looked on FB and come to find out this chic never worked where he worked she actually worked in the same place my cousin worked. My cousin even knew the girl. Smh. This girl never ever worked with him. Again I played it cool until more and more information came up. This man broke my trust previously but my slow behind have him another chance so I had a right for my suspicions. I thought he would give me the common decency THIS TIME to tell the truth. Found out he was talking to her behind my back. My thing is if it’s innocent then lie for what? I’m at the point now where I just laugh at him trying to explain this to me. It’s funny. The lies he comes up with. He sent me a screenshot of him texting the same girl and him telling her he can’t talk to her no more blah blah blah because it’s causing issues blah blah blah. Found out he unsent that on iPhone lmao! He sends my a audio message saying “I’m just going to cut everybody off and just be me and you yadda yadda yadda” like his tone was as if he didn’t even want to do that. I responded you don’t have to you can keep all the homegirls you want to i don’t care. I really laugh instead of cry it hurts but it’s sad the length he will go to. We were suppose to go to a beautiful gala this weekend with my family and he will meet my extended family. Now I am think I will get pretty and go without him. I’m just so over it. I’ve done so much for him I’ve been patient, dealt with drama, I’ve given him yet another chance, I make sure he is good his health is on point etc and I don’t mind it comes natural. Yet he still has to lie to my face. He met my mom and she loves him. I haven’t told her yet. I know she will be disappointed. If I’m my shoes what would you do?