How to NOT Can Tomatoes

I had planned to write a highly motivational piece on how easy it is to can tomatoes.  That didn't happen.  While visiting my grandparents over the weekend I got bushels and bushels of tomatoes. Enough to cover a large portion of my counter 2 or 3 deep:

I used the same method for skinning and dicing/crushing the tomatoes as in my post, here, about freezing tomatoes.  I was very slow at first, but managed to get pretty good at it by the end.

Then I followed the directions that every blog on canning will tell you:
~Start a canning pot boiling
~Sanitize your jars, lids, etc.
~Heat your tomatoes and liquid (juice or plain water)
~Pack tomatoes into jars, pushing down with handle of wooden spoon
~Add acidity (I used lemon juice)
~Add liquid and use spoon again to release air bubbles
~Wipe jar and apply seal and ring
~Put in boiling canning pot..... This is where things went awry

The very first jar I put in broke immediately.  It must have taken me too long to fill the jars and this one cooled because it cracked the second I put it in the boiling water.  So I put the rest in, with no breaking, but the kept tipping over... Probably because my electric burner is a bit smaller than the canning pot so it sort of leaned a bit.  Once I got them all in though, they seemed to stand okay without knocking into each other.  Although I think that two of them did knock at some point, because when I checked on them later there were tomatoes floating around the entire pot and a clearly broken jar just floating around... Yay.

The others seemed to work okay, and sealed quite well.  Of course now I'm extremely worried that I did something horribly wrong and they'll all spoil before we get to use them.  What a terrible waste that would be.

And I'm sorry to disappoint if you were hoping for the horribly photographic evidence; I was far too distraught to think about anything other than all the hard work I'd put into peeling and dicing the tomatoes just to throw them down the drain *sigh*

Have you had a bad experience with canning?  Do you know what I did wrong?  Do you just want to laugh at me?
~Nicole