I think your friend is someone who likes to joke around and didn't know you would be offended by his rude comments. That's why in his message he seems to think it wasn't a big deal and he can contact you just like how he usually does.

So my advice for you is that you either:

(1) Don't take things so seriously, don't mind his rude comments and yelling, he might not have been serious about them, might just be joking around or teasing. You don't have to be so polite to him and can be rude to him back.

(2) Accept that he can be a rude person and maybe that one time where he yelled at you was only because he was in a bad mood, overall you said he helped you on many things whole heartedly so he may be still a good person at heart.

(3) Tell him that you don't like it when he is rude to you or yells at you and see if he apologies or what his reasons were for doing that.

(4) Stop being friends with him if he continues to be rude to you despite you telling him that you get offended and don't like it.