Okay, your post is a little hard to read, so I'm going to try to break it down to what your questions are. I'm assuming from your post that you are male and your sex partner is female.
the shit is i getstimulated by direct stimulation like head n shit...now after thats over....he jusst dies on me and this shit is frustrating...makes me feel like im useless.
Do you mean that you orgasm/ejaculate and then your erection goes away?
i know bout something called performance anxiety but shit how long is that supposed to last ?..
If so, then what you mention above isn't "performance anxiety," it's something totally normal called the refractory period; it basically means that you ejaculate, then your body has to recover for a little bit before you can get another erection and possibly ejaculate again. Everyone's refractory period is different.
If what you mean instead is that you're *not* orgasming/ejaculating, but that you get worked up and then go flaccid, that could indeed be what you mean by "performance anxiety"--basically, that erections tend to stick around till you get worried about them and then they make for the door. That, too, is perfectly normal.
The best thing in either situation is to realize that you and your partner can both deal with this--there are plenty of things you can do without an erection being involved. Meanwhile, when you aren't concentrating on having an orgasm or an erection, you can relax enough to make those possible.
About the condoms: have you tried a variety of condoms? Because if you're only using the ones commonly available in the drugstores, yeah, those can suck. There are a number we like around here: Kimono ultra-thins seem to be the favorites of a lot of Scarleteeners. Also, condom-safe lube can make sexual activity a lot more pleasant--and safe (keeps condoms from breaking!)--for both partners.
"And when the answer that you want/Is in the question that you state/Come what may..." - Coheed and Cambria, "Blood Red Summer"