Learn from your mistake and move on. Don't let it get to you.
You could try a negative split next time.
Start at something like 1:50, every 400m or so work it down by 1s. So go 400m at 1:50, 1:49, etc.
Last time I did a 2k I held about 1:40 for 1500m before hitting the wall and losing all my rhythmn. It was a mare to say the least, but I didn't let it get to me.
Unfortunately, I've since stopped rowing so I haven't done a 2k (or any training) for a while.