I'm a bit stingy as a DM, currently handing out about 70% of the recommended wealth to the characters for campaign reasons, but your DM seems to have a totally different view of gear. I might break a character's main weapon in the course of an adventure, but surely it would be replaced in the next session by something they could use. And at that level, I'd expect a character to have at least 2 to 3 lesser magic items they can use.
Even if the DM has 15 years of experience, that doesn't mean he's all that familiar with how to run a 3e/3.5 campaign. When I switched over from 2e, it was a big learning experience, and there were many places where it seemed like the damage was high. However, I've since learned what to expect in the current game system, and understand why that damage needs to be there. It sounds like your DM hasn't come to that realization yet.
What's worse is the dude killed your horse. I only kill or steal horses when parties foolishly neglect them ("Hmm... There's a number of large predators in this area, but we'll only be away from them for half a day. Let's just let them graze in the wide open. What could go wrong?"). You paid to have your horse stabled for 2 months. You should be rewarded for that, not punished. That's a huge sign of a very bad DM, IMHO.
As for how to handle things...
It sounds like you are in other groups, and not having much fun here. Those are both strong signs you should leave this group. Personally, I'd try to get my character killed in some kind of spectacular blaze of glory fashion that will leave a lasting memory, and hopefully it will be in a situation that could have easily been prevented had you had the proper equipment and wealth of your level.
![Devious :] :]](http://www.enworld.org/forum/images/smilies/devious.png)
Maybe, just maybe that will help wake up this DM to the error of his ways...but it probably won't given his horse episode.