Depends on the bad stuff that Boy A does. Who broke up with who? Does he call you because he wants to know how you are or because he's being clingy and controlling? It sounds like red flags are going off in your head about him.
Also, by definition, if Boy B doesn't know you, he can't love you yet. If he's interested in you, though, and he's nice, I think it would be worth getting to know him better if you're interested too.
You need to choose Boy C: The boy you haven't met yet.
If you and boy A have had trouble in the past, and you are having doubts, then you don't need to be in a romantic relationship with him. You can be close friends. You can leave it the way it is right now and just see where it goes. Maybe you'll get back together in the future, maybe you will just be good friends.
' Boy B I've only known for a few weeks but he already claims to love me.'
From my experience, you need to avoid this dude. He doesn't know you well enough to be saying things like that.
I've known several guys who insist they are madly in love with me, but the thing is, they don't have to live with me. I am NOT an easy person to be in a relationship with. I'm freaking crazy. I mean, really. That's not a BAD thing necessarily, but these guys can't handle it. If he can't stand being on the phone with you when you cry, and that is something you NEED in a relationship, then you don't need him.
Choose growing up before you get into relationships.
Boy A is likely only attentive because he's hung up on you and wants you back, but he obviously doesn't respect you or you plain don't fit if we are to keep in mind the bad history. People that are nice only with a reward in mind, generally flip if you don't give them what they want, so it might be potentially dangerous to be so close to A, he might actually even accuse you of leading him on.
If Boy B isn't that interested in you, and neither are you in him apparently, you shouldn't just be stringing it along. Your statuses aren't limited to together with x, y, or z, there's being single as well, and when it comes to love, it's a better idea to wait until you're older (I see you're 16), so you can understand people's intentions and your own feelings on the subject better. If you're one of the ones who feels lonely and you'd really rather not be single, I'd be looking for someone who I'm actually fond of, as you don't seem to care for B.
You seem to have low self esteem and think you either don't deserve better, or can't get better. Why settle for either if their treatment of you is anything but stellar? There are many fish in the ocean and you have sampled only two bottom feeders. Go for the best catch of the day. It can only get better.