Im getting an apartment with my SO and he has two kids that don't live with the him

Hello,

I am trying to gather advice on how to go about telling my boyfriend my mindset with sharing a place with him on top of having the children over etc. I simply want to try and explain to him that I am afraid because he makes it sound like it'll just be us two most of the time but they will be coming over more and more as they get older. I honestly am really excited about living with him but as bad as it sounds, at this point: I would rather it be just that, us two. I am already feeling like I have to implement children factors and we are both in separate apartments now. I love this man and I want to make everything work. I'm afraid I'll loose my individuality in my own home. I'm very independent and an introvert hardcore and I enjoy my own company just fine. My space is mine and my apartment is my safe space. If the kids start coming over regularly and without even having a heads up I will feel like I'm drowning and feel like I literally have to leave my own home to get any sense of relaxation or solitude. That's not fair to me but I don't want this to come off as I'm not on board with his children being a part of my (our) life because truly I am. I don't know how to say kindly that I'm not wanting to mother them to be honest because I still want to focus on just being his girlfriend and the girlfriend that's living with him ..... does any of this make sense or am I overthinking? Other people I've spoken to tell me to leave him because they aren't willing to take on the children and stuff but I love him and I don't plan on going anywhere. I simply want to be able to convey my headspace about this.... HELP ME