You've got 5 ish weeks until the marathon. You've not done a long run for 3 weeks (precisely the time the long runs should be done). You need to build back up to running the long runs and taper all within 5 weeks.............
How much running have you under your belt? What was your longest run, and how many times did you do it?
Would you really be happy with 'just getting round'? With a target of 3:10 you clearly are very good at running, so would you really feel happy with not getting near that target?
It's a really personal decision about pulling out or not.
I was injured during my 1st marathon training and had more weeks out than you, I got back into running about 8 weeks before the marathon and built up to 17 miles as my longest run.i was woefully undertrained. I had hoped (pre injury) for 4:30, it took me 5:48. Was I glad I did it? Yes. Was I satisfied with my result? No. Should I have done it? No. Did I enjoy it? Yes/no/can't actually remember part of it.
Having had the experience of doing a marathon undertrained, I would never ever do it again like that. I didn't feel what I thought I would feel after, the sense of achievement wasn't there and I still feel like a 'fraud' because most of it was spent crawling forward rather than sprinting with the ease I spent months visualising!
Good luck with whatever decision you make.
It IS only a race, even though we all think it is life or death.