Help with my plums!

[weedonleg]

I've just been outside to look at my (rather neglected) plum tree.

Holy-moly! It has about 1000 plums on it, loads of branches have snapped and the plums are practically touching the ground. A quick google told me that while I am a little late, I need to prune the tree as snapping branches aren't good. So I've randomly cut off all the branches that are under strain and the tree certainly looks a lot perkier, although I'm no hairdresser. Obviously there are now about 200 plums lying on branches on the floor, which sadly I have had to sacrifice for the greater good.

Anyway, I google again, and see that I really should have (back in June)thinned to one, or a pair of plums every 8 cms. Really? Do I need to do that as well as the savage pruning? The plums are still slightly small (bigger than walnuts but smaller than plums) but they are hanging like bunches of grapes, and nowhere near ripe yet. Should I thin, or is it too late? I'm most concerned with not killing the tree, less so about the no. of plums I will get this year.

Just off to look at my apple trees...

Many thanks!