Thanks in advance for any wisdom or tips!

I have this frame and fork I picked up for free off of Craigslist. It's an older Trek frame w Ishiwata 022 tubing.

When I first brought it home it was very ugly. I started sanding and before I knew it I was determined to clean the bike of all of it's old paint. I pulled out my belt sander for some of the heavy lifting and used whatever sandpaper I had on hand. Some of the sandpaper I used was pretty course, maybe 80.

The finished product looks really nice but now I've done some of the online research I should have done before I started the project and I'm concerned that in my haste to sand the frame I might have ruined the integrity of the steel.

Is this project no longer safe? Should I throw the frame out?

It still looks fine but so far my investment is only time and safety is very important to me.