Advice

So me and my boyfriend have been dating for almost 4 months and the other day I saw a tinder notification on his phone . So I went through his phone and found out he’s been talking to other girls . I was so hurt and disappointed . I wanted to leave so bad but I’m so in love with him and I want us to work . I talked to him and all he could say is that he’s so sorry and that he doesn’t know why he did it . I don’t know if I wanna give him a second chance or just end things off .