Help! Relationship advice

I started dating this really nice guy a month or so ago but I can’t seem to shake some insecurities I have. Because of past experiences I keep thinking about what if he’s cheating on me or what if he cheats on me. He’s the worst texter i have seen but most guys are, but sometimes it makes me feel unimportant. We’re really good when we’re together but when we’re apart I kinda start to freak out. I’m not sure what to do, should I talk to him about what I’m feeling? He said he’s been cheated on before, but I never asked if he’s ever cheated. Should I just keep my mouth shut?