Not the end, just a set back. I've had way worse and resumed running pain free, albeit short and slow. Consult several docs for opinions. Then go with the best recovery option, don't jump on surgery necessarily. But, if you do, like me, rehab the hell out of it.

Good luck.

Doc said no need for surgery and put me on rooster combs (Synvisc).
Now I have chicken stuff in me.
No running for 4-6 weeks. I'm doing more swimming and biking and weights.
Is this a permanent injury?

Synvisc has about a 50/50 history. My understanding is sometimes a tear will settle back down and not become symptomatic. However, you have an insult to that joint and will need to play by your docs rules. Depending on symptoms a meniscus tear can be "cleaned up" surgically with few long term implications. But, I'd play it conservatively and see if you can avoid surgery.

I tore my meniscus rock climbing. With the tear I was able to ride my bike and rock climb no problems, and I could do one, or possibly two runs but after that my knee was too painful. They were planning on chopping the meniscus out during surgery (about a year after the tear) so that I could run, but once he got in there the surgeon decided to sew it back together. I had my knee in a splint for three months after the op (though I was allowed to do easy riding on the turbo on flat pedals after a couple of weeks) which sucked, but I got used to it. After that I resumed running etc and now have, apparently, a perfectly health knee. That was about 5 years ago and I've had no issues with my knee since.

Mine was 6mm. It took me close to a year to get to the point where I got the MRI that showed it. Thought it was arthritis, but when I finally suspected meniscus, I intentionally ran it hard a few days in a row to see if the clicking, popping and other stuff would fully show up-it did! I was only able to run twice a week and the day after the run was just throbbing pain and had to use handrails going up and down stairs.

Ended up have a meniscectomy done and was able to get back to running after 8 weeks, was biking easy on the trainer 3 weeks out (maybe 4).

Now I do more prehab exercises and more active warm up stuff before a run...but I'm back to running with no pain to the joint.

Meniscus wearing and tearing is normal. This becomes evident as we reach the age of 30 and beyond. MRIs of asymptomatic knees will show tearing as well. It's even possible you've had the tear for a while and only became symptomatic recently. Either way, menisectomies are no better than placebo or physical therapy. It is likely you can manage this yourself if you avoid making it worse. The injury will likely scar down and not bother you in that case. Find a PT if you are unable to manage.