O. K. Take a deep breath and chill for a minute. I understand that you are freaked out, but we can fix this problem. It's not hard to fix.
You're suffering from what's called premature ejaculation and it is a very common problem, especially with younger men who haven't learned how to wait. There are two techniques that will enable you to correct the problem. The first thing you need to do is learn to recognize your premonitory sensations--the feelings that you get just before the point of no return.
So what you will do is masturbate until you experience these premonitory sensations, then you will use one or both of the following techniques. The first technique is the squeeze technique.With this technique, you firmly grasp the head of your penis, just below the coronal ridge (the part of the tip that bulges out) and squeeze your penis until the urge to ejaculate subsides. Then resume your self-stimulation until you feel the premonitory sensations arise again. Squeeze again. Repeat this cycle for as long as you can. With practice, you will develop the skill of waiting longer and longer.
You can also try the stop/start technique and see how this works for you. Again, when the premonitory sensations arise, simply stop all stimulation, stop touching yourself, and wait until the feelings subside, then start stimulation again, and keep repeating the cycle. You can practice both techniques with your wife and you use these techniques during intercourse by stopping thrusting and/or pulling your penis out of the vagina and squeezing it the way I described above.
I would also suggest that you don't jump into intercourse until you've given your wife an orgasm through manual or oral stimulation. Once you've given her pleasure, then begin intercourse. This way you won't be so worried if she doesn't orgasm in intercourse, since you've already given her pleasure beforehand.
If you find it easy to achieve erections and can ejaculate more than once in a day without a problem, you might also consider masturbating to orgasm just before you make love with your wife. This will help diminish your urge to ejaculate right away.
Let me know how you both do and hang in there. We can get past this problem and we will.