We have been dating over a year now and lately, we argue so much. He gets so upset if I don't reply to his text messages , answer his calls regardless of what I'm doing.

He right away attacks me verbally saying I do not care, I'm selfish...

Kick him to the curb... he's obviously verbally abusive

What has changed? Or what do you think has changed.

To continue to have a good relationship, he must respect that sometimes you are busy and can't reply right away. His verbal attacks do suggest that he has something on his mind. Very possibly, something he hasn't told you.

He may have simply decided that you are his property, which you are not, property he wants to control and is afraid he will lose. He learned to verbally attack from someone and he's probably listening to those old tapes in his head. When people are scared, they yell, unless they learn differently.

I remind you that the dating process requires staying together long enough for you to discover exactly who the person you are dating really is. I recommend 8-12 months before you can start to gauge a person's behavior as authentic.

So, you've been dating a year and this is how he treats you? If you discount all the earlier niceness as "courting" behavior and not truly authentic, then it is safe to say that you are NOW dating the guy he truly is.

Ignoring all that has happened before, would you date someone who acted this way? The way he is now is very likely exactly who he's going to be around you forever. So if you decide you're OK with all this, then be sure to wear your seat belt. It's going to be a bumpy ride.

You don't have to stay with someone who treats you this way just because you have been together a year. The reason you stayed this long was to find out how things would go, and now you know. Even if you break up now, this is still considered a success.

Thank you for taking the time on this matter. I couldn't have heard better then your advice. Obviously has opened my eyes.
:)

Hello,

Nothing has changed. I think that things are getting worst each day. He seems to calm down every time I say I'm done with the relationship. But I cannot go on like this anymore. I told him last night that we should break up...

You don't tell him in advance you "think" you two should break up. That's more arguments waiting to happen.

No, you tell him that you are done with him. You're ending it. It's over. When he asks why, you tell him it's him, and you're done. That's it. The more you talk, the more fuel you give to make it worse.

You're breaking up, the reason is him, and you're done, wish him well with his life, walk away. Then break off all contact, change your cell phone if you have to, make it clean and permanent, don't look back. No reason to.

I agree you need to TELL him you are through because telling him "I think I will break up with you'' is only opening the door to him guilting you into staying for more verbal abuse.
A guy like this is either very insecure
OR very controlling. If he is controlling then it very well could be that he is only verbally abusive now but later when he feels more comfortable with things he could very easily prove to be physically abusive as well.