Singlespeed & Fixed Gear - track wheel on a road frame

My rear wheel is about 20cm narrower than the space between the dropouts.
Do I need spacers on the rear axle or is it okay to just tighten the bolts down and "bend" the frame into the narrower spacing of the wheel?

It is an aluminum frame and it bends very easily. In fact, you can hand tighten the bolts pretty easily closing the 10cm gap on each side. I have been riding it this way for a few weeks now with no apperent problems.

My question is if this is stressing my frame, will it cause the frame to break someday, and am I going to die?

I think you mean mm not cm. Spacers and possibly a longer axle would be the best solution.

I would add spacers.

am I going to die?

eventually

I would not do this with an aluminum frame. Spacers are a far better option, and depending on the hub you may already have plenty of axle.

What Barba said. It's not okay to bend aluminum. Fine for steel though.

I found myself in the same situation lastnight albeit with a steel frame when I started to convert my bianchi trofeo. My question is can I put spacers right on the end of the axle inside the frame or do they need to go inside of the hub?

That reminds me of something I saw earlier:
A messie I saw riding had an MTB frame but rode fixed. What he had done was cut a pair of track ends from ~7mm steel sheet with a largish area of metal left above the actual ends, drill them, drill the dropouts of the frame and bolt the track ends to the inside of the dropouts. The axle ended up south of its original position of course.

You get 120 spacing, track ends, the nastiest/coolest DIY look and a bit higher bb + a bit more aggressive frame angles. I tip my hat to you, Unknown Messenger.

I found myself in the same situation lastnight albeit with a steel frame when I started to convert my bianchi trofeo. My question is can I put spacers right on the end of the axle inside the frame or do they need to go inside of the hub?
It depends on the hub. You can do that as you say or you can place spacers between the cone and locknuts.

I did a combination of the two for the fixie conversion I built; added about 7mm of spacers, and bent the dropouts/rear triangle arbitrarily so that the rear wheel installed easily. Later I had my LBS check the alignment, and they said it was fine. Later as I was adjusting for chainline, I ended up with more spacers on one side, and now I only have few threads engaging on my drive-side track nut, which worries me a little.

So I recommend you skip the actual bending (especially because it's aluminum), and the peace-of-mind is absolutely worth it (I basically bought a new bike just so I'd feel safer with more 'solid', fixed-specific components). Measure your axle, the thickness of your dropouts, the track nuts, and calculate if you have enough room for spacers. If not, find a new axle. Do the job right, and make sure you can easily install the wheel with the correct alignment/chain tension.

Thanks you guys for the advice.
I went and got some 2mm spacers and ended up with only 3 of them on each side. So my estimate of 20mm was a little off.
Using two cone wrenches to remove the inside bolt, it only took about 10 minutes total, including remounting the wheel.

Vertical dropouts with the magic 42-15 gear combo.