am I wrong for being upset about this?

My boyfriend and I live separately. We were texting and suddenly he started replying really late, and it took him so long just to say "yeah". 
He then told me that his cousin was over, and I know that when his cousin is over he barely texts back and doesn't really make an effort for a conversation, so I told him to talk to me later when he's done hanging out with him.
He said no and that he wanted to keep talking to me, but I prefer a full on conversations, not really much of him just going "oh" yeah" "okay" "true". So we did keep talking, but it ended up being exactly what I thought it would be. Constant late texts and no effort at all to talk to me which made me a little upset since he claims to want to talk to me, but doesn't. I just told him that I'll talk to him later since there was no real conversation going on, and that he should just be hanging out with his cousin and having fun, and he got mad at me...
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I did stop replying all at once at one time, but he kept texting me to text him back and was spamming my phone