Oh hell Wenty I'm sorry to hear that. I was tripped at mile 19 last week in Paris and limped home in 4:21 instead of the sub 4 I was comfortably on target for up to that point.
Like you I felt it had been a wasted winter. A week on, having recovered a bit I have recognised that 5 months of hard work is never wasted and I've managed to get myself a place in another marathon on 31st May to have another shot at it.
Give yourself some proper recovery time, regroup and have a think about how you can best use the hard work you've put in. This was beyond your control - yes, it's a pisser but it's no reflection on your ability to get the job done.