I don't think you have screwed it up. You are still going to have beer, and probably quite tasty beer at that. With a protein rest (133ish) you can break down the proteins until they are too small to create proper head retention. I don't think you will have a problem with head retention though, because the hop polyphenols also help.
The reason most of us recommend a single infusion is because it is easier, and you will still get great beer. I mash in somewhere between 149 (dry beers) and 162 (Session beers) depending on how fermentable I want the wort to be.
RDWHAHB. This forum has a lot of really smart people, who know a lot about making beer. Sometimes we are known for talking over people's heads because we want them to make the best beer they can make. Remember, Barley and hops want to become beer. It takes a lot for us to screw that up.