Ecclesiastes,
With some persistence you will probably be able to pull your grades up. Like you, I started going to law school evenings and working during the day. The second and third year classes are often not curved and the classes are often smaller - giving you a chance to get to know your professors. I went from a 3.1 to a final GPA of 3.45. That might be enough to get you cum laude. And with hard work, you might be able to write onto law review. And your background is pretty decent, and you at least have some patent experience. And a lot of folks I've talked to have said that they anticipate the hiring freeze to start thawing in about 6 months.
But remember - there are three big factors working against you
(1) You're having trouble finding work in what I think is the biggest patent prosection market in the US. (2) And law school pedigree is very, very important for the big employers.
(3) I hate to bring this up, but I think your age also might be working against you. Employers will look at you and think that you might have priorities other than getting all those billable hours in. Also, they might think you carry a sense of entitlement.
I had to make the same decision 3 years ago and I stuck it out. I am not so sure I made the right decision, but there it is. It's not a nice thing to have all this non-dischargeable student debt hanging over your head and to be unemployed while your wife becomes angry and bitter over the apparently useless JD. I don't know if you have kids, or if you want kids, but your wife might not want to support you forever!
And remember, if you decide to go back to your old career, you can do it a lot easier now than in another 2-3 years. You would need a pretty good story as to why you didn't get a job in patent law.
We never know at the time we make a decision whether the decision will be correct - all we can do is to gather as much information as we can and then act on it. Things usually work out. At least that's what I keep telling myself.
Hope this helps.