Advice time.
If something is bothering you, should you definitely talk to the person you are having the problem with? I have little hope that things will change or opinions will change, so I can't decide if it's worth it to talk to said person, or for me to just deal with it myself. If I can deal with it. I don't know...I'm just having a hard time and I'm really bothered by some things lately.
Anyway, what do you guys think? Talk to said person, even though things will likely not change, or keep my mouth shut?
Well, if you're not going into at least a little more detail, it's hard to give any useful advice. I can think of half a dozen different situations where what you said may be a sensible summary, with different advice/reactions. Is it someone who has some sort of power over you (boss, manager,...) and who might get upset/angry if you tell him/her? Is it someone who you're close to and might be offended, breaking a bond you don't want severed (brother, niece,...)? Is the thing that's bothering you something that, if left unchecked, might drag you down along with him/her (drug use by partner, embezzling by a co-worker,...)?
Depending on the situation, advice might be to try and get away from the person without hurting them, to try and talk to them as inoffensively as possible, to make it very clear and obvious that you won't stand for what's going on, to casually mention it but not press the point if they're unwilling to admit fault/flaw, to try and involve a third party to either mediate or support you,....
In all cases, though, "rushing in unthinking and going for the attack" is probably the wrong idea, as is trying to "just bottle it all up and "deal with it" by yourself" if it's something serious. Try to stay clear of danger to yourself and loved ones, try not to blow up something good you have going on over trivialities, but be firm and honest if it's something that needs addressing.
Sorry for the sort of wishy-washy advice. Last words: you're obviously in the right, and s/he is a jerk/bitch for doing/saying/acting as they do.