That's a difficult stretch. And with practice it's possible to do (as discussed above in this thread).
As a practical matter, you don't need that particular stretch playing the B7 chord. Just play the 2-4 and the 2-6 and call it good. Nobody will care you didn't go up to 7. And if you really want to put that extra little zinger in there you can shift to B on the 7th fret. You can play it there until you're better able to handle it on the 2nd fret.
The key of E is easy to play until you get to the B chord, then it become a little difficult. That's why playing in the key of A is such a sweet option. A, D, and E are all right there and easy to grab in the open position.