As you probably already know, that's the yetzer hora talking, on several different levels. You have a tremendous awareness of the gravity of the aveirah, and the yetzer hora will gladly try to twist that valuable koach that you have. You can't let him.
I actually saw a piece by R' Yeruchum that reminded me of your situation. In a way, I respect your horror at what you've done, and your desire to smash the object that it was done with. However, R' Yeruchum points out (discussing Yackov going back to retrieve "pachim ktanim," small containers) that for tzdikim, everything they have, even the smallest value, is important and must not be wasted. Not just because of bal tashchis, but more importantly - if Hashem gave you something, that means you have it for a specific purpose, and you're supposed to use it.
Furthermore, smashing your ipod/computer/etc. is an easy out. It strikes me as a way of "undoing" what you did by breaking something in the physical world - imagine if you could affect that same change on your internal world, destroying the things that make you have that compulsion (which is what we're all working on here)! Obviously, the yetzer hora would MUCH prefer a smashed ipod.
You awareness causes you to feel bad. But it should also push you to do whatever it takes to improve - and you KNOW that the best way to do that is to motivate yourself. Unfortunately, we've all gotten used to certain aveiros, and despite our outward horror, it seems that on a deep level, these things HAVE become mutar to us, as much as we detest them. We have to do teshuva, and our personal avodah of teshuva is clear - using the 12 steps, the handbooks, etc. Renewing our energy and starting anew with faith in hashem, and good spirits. What "feels" right, and what "feels" like the type of thing a tzadik would do may, in this case, be very, very wrong. The Yetzer Hora is good at that. To quote a rebbe of mine, "I like to give credit where credit is due. Let's face it - the yetzer hora does a damn good job." Our job is, primarily, to improve, at all costs. That's real avodas hashem, that's real teshuva.
And truthfully, the idea of depression after an aveirah is famous - R' Chaim Shmuelevitz discusses it in the topic of the chet ha'egel, and his basic point is that when we have a yeridah, the depression that follows has the capacity to bring us to totally new depths, far, FAR below the original aveirah.
Don't let that happen - laugh, do something to cheer yourself up, be happy that you have the strength and courage to try again, and to avoid falling again. And remember how great the reward is for not falling for a minute, a day, 2 days...for however long you restrained yourself, you deserve congratulations!