I appreciate that you couldn't ever have known or suspected that he was violent if he never showed those behaviours to you, and that must be a terrible shock.
But you have said he shouted, snatched his phone out of your hand, 'went quiet' for long periods and disappeared (under the pretence of spending time at his sister's) during your relationship and now sees his daughter 'only when it suits him'? To be honest, there are already quite a lot of red flags there - obviously not ones you'd expect to see leading to violence, but certainly things that would not make me think he was a lovely guy.
If someone listed those things to me about a man, I wouldn't assume violence, obviously! I would, however, think they were not a nice bloke at all and I wouldn't feel they were a lovely, fun person to be around. I'd think they were a total prick. I definitely think you can raise your bar for what you consider to be a good man.
Regarding the awful, awful things you've now learned about him - my god, that must be a horrendous shock and I hope you've got enough support. It's understandable that you're confused about his Jekyll-and-Hyde character too - but I think some people are capable of being a cheerful, fun sort of person with everyone except their actual partner. If he isn't your partner and he doesn't live with you, I'm wondering if the things that typically trigger his horrific behaviours are things that simply haven't arisen because you're not together and while you were actually dating he was in fact busy stalking someone else and saw you as a fun distraction rather than his property, which I imagine is how he saw his other girlfriends.
You say he sees his daughter 'only when it suits him' which to me suggests that he currently has everything his own way. I suspect his violence/aggression may well be the kind that surfaces when he doesn't have things his way all the time, and that's really worrying.
FWIW, my ex-partner was also 'the most happiest, fun, chatty man ever' to most people - and before we actually got together seriously, he was like that to me too. It was only once the relationship was serious that he became abusive, and only after we actually lived together that he became dangerously violent.