Sometimes just getting it out helps. Write it all down; describe exactly what made you angry in great detail and try to include what specifically made you angry and see if you can figure out why exactly it was so significant to you at that moment. If it seems like it was a silly thing then there was likely something else going on between you two or within yourself. Just pour out all the things you've been feeling and why. Venting and understanding the cause of your feelings, in a neutral way where you won't risk being judged or ignored may help to resolve things. Or at least help with the irritability you've been feeling in general.

Then on separate pages write out how you met this friend and why you became friends. Write out the things you like about him and maybe some good memories that you shared. See if it balances out any of the anger in remembering why this friendship mattered to you.

Once you have a solid grip on it all you may, hopefully, be able to talk with him about it calmly and without anger. Try saying something like "When you (did or said something) I felt angry (or irritated) because (the reason it made you feel that way)." That way you avoid accusations that could make him feel defensive and not listen to you. It might sound silly but I've actually had a lot of success using it in conflict when the other person and I both were so angry that we weren't really hearing each other.