Should I dump him???

I’ve known my bf for 6 months but we’ve only been dating about 3 months. In the beginning while we talked he was getting rid of his ex’s and such before we were official. So today we’re on the phone like normal and he tells me his ex called him that morning but he declined it (the ex that won’t let us be) and he’s like hold on babe I have another call coming in . I’m like is it her and he’s like no then hangs up . 15 min later I call him back he says it was his dad. Calling for the score of the game . I’m like ok why u didn’t call me back and he’s like I’m sorry I forgot then he’s like lemme not say that , I called my ex back because she txt me saying someone in our class died ...(which was true cuz he shared it on fb) so I’m like ok but it had me wonder if his dad really called . And he’s like yea his dad called . Told me he couldn’t screenshot it cuz the call came in while we was otp and I either trust him or not am I’m like that doesn’t even make sense but ok ...then I guess he gets tired of hearing my mouth then says I’m sorry and I’m like what u sorry for and says that was her calling me but by time I switched over she hung up so I called her back . And I asked why he lied and he said because he knew I’d trip if he told me she was calling . And he had to keep adding to the lie cuz nothing could get past me ....he apologized again and said it won’t happen again

But you know how that goes ...who’s not to say he won’t lie again . Yea it’s a red flag he still talks to his ex but supposedly they dated 10 years ago but been on and off having sex when hes in her state (she’s his moms neighbor) she had a baby with someone else and had him thinkn it was his the first trimester . That’s why he stopped hooking up with her and it’s been 2 and a half years since then supposedly. But he says they don’t talk like that anymore but they do check in during a death or hurricane season etc

What should I do ??