That's a crap ton of yeast. There's a lot of trub mixed in but a good portion of that is viable yeast. The only issue you need to worry about is flavors from those dark malts carrying over. Pretty minor concern but if you take a portion of that yeast and make a starter out of it, you'll be good to go. I wouldnt try to rinse it.
I agree, at this point it's one of those "go ahead and use it, you'll do better next time" things.
It took me a bit to really learn how to harvest yeast, so I certainly didn't laugh at your photo. What works for me is, I start by boiling mason jars and the lids and bands. This sanitizes them, and the water I'm going to use. I take the jars out hot, and leave them 90% full of the boiling water. I place the lid and band on a little loose. I let those cool. I also sanitize a large 1 gallon or half gallon growler and fill it up with any left over boiled water. After I rack my beer off the yeast cake, I add about 1/2 gallon of water from the growler to it, swirl like crazy and then pour it back into the (now empty) growler. After 5-15 minutes, (you'll have to keep an eye on it) most of the trub will have settled. So one at a time I empty a mason jar and fill it up with the liquid from the growler. It won't look like there's a ton of yeast in it, but there will be a perfect layer 1/4-1/2 inch thick on the bottom of the pint size mason jar after it has been chilled for a day. Sometimes when I'm pouring into the mason jars I disturb too much trub in the growler, and I let it settle again for a few minutes in between each mason jar. I usually get about 4-6 per batch. Each one of those contains about 30-50 mils of pretty thick yeast slurry after decanted, enough to do a 5 gallon batch if you make a proper starter and don't let the yeast in your mason jars hang around too long. Lagers don't last very long at all, a month at best. Some ales I've used as much as 3 months out but always make a giant starter. A lot of times I will decant and pitch 2 of the mason jars instead of making a starter. I'll see if I can get you a pic here in a bit but there's plenty of articles and youtube videos out there on doing this so I think after you practice it another time or 2 you'll have it down pat.