Read Carefully Friend 
In my opinion, the problem is not your verbal. It's the stress. It's your confidence! And your approach to the test.The variation between your scores in the mock tests and your scores in the actual gmat have only this one cause.
1st... why do you put so much importance to the GMAT ?
You got a bad score! Big deal. You're still alive and well. The war is not over until you say so.
Tonnes of people overcome the odds and get a great score on the gmat every year. Proof--GMATclub. In the end, it is just the test. Recommend you to not tell anyone next time you take the test. So you don't have to tell anyone what you scored except yourself.
2nd... look at your "A day before the test" section-
> " I felt that I am spending more than 3 minutes, even though I knew the way to solve them."
> "After the RC, I felt that the questions became easier and I knew I made mistakes in the first passage."
>" Unfortunately, I had to guess some and solve some, but even the ones that I tried to solve seemed to me at that moment very hard. I couldn't focus and apply the techniques and rules, both in CR and in SC. "
Read those again. And please ask yourself:
1. How did it matter if you actually did take more than 3 minutes for some questions ? Some questions are solved within 30 seconds, probably even less. So doesn't the time average out in the end ???
You still scored 49. Staying calm could have helped you score even better
2. You 'felt' the questions became easier. Why do you think about previous questions at all ? It
DOES NOT MATTER if you get 3 in a row wrong. You can recover! What matters ?
THE QUESTION AT HAND Focus on the question at hand sir. Not the questions you answered, because you can't go back anyways and you definitely can't predict the next question or its difficulty level, so might as well focus on the one in front of you.

Imagine what would happen if tennis players kept thinking about the last serve wich dey "couldn't" take advantage of rather than the ball coming towards them at 90 miles an hour??? So focus on finding the solution to the present problem and not its difficulty level. It could be experimental. Perhaps the GMAT test makers considered it tough. It could be anything. So do not predict while you're in battle. Defend and attack as required

3. Suppose you got some questions wrong in the end, so what ? For all you know, the last few questions matter 'as much as' all the other questions in the test. On GMATPREP (which follows the same algorithm as the original test software), i had got the last 4 questions wrong in the quant section and the last 3 questions wrong in the verbal too, still i scored 700!!!
I have faced this too. You know what i did ?
I practiced more questions.
Beginning with the OG or wichever you find easiest

, do questions in sets of 10,37 or 41. Then
ANALYSE. Analysis and re-work is way more important than the source of preparation. The method means everything

My dear friend, you are extremely intelligent, your average on mocks hovers around 680-720. The problem is confidence in yourself. The way i see it, your average score on the verbal is 33! Thanks to the 800score's calculator, if you had just scored V: 33 in this test, with a Q: 49, you'd have reachd 680-690. If you actually keep your nerves next time... you will cross 710

You have done it before man, you can do it again. I'm an atheist, but i read that book called "The Secret", and it did have one good point. "You get out of bed in the morning feeling bad, your whole day goes bad. You get out of bed feeling happy, your whole day seems to go great." Its all in the head really. The GMAT is just another test.So work on your psychology more than your skills. ITS ALL IN YOUR HANDS AND ITS ALL IN YOUR HEAD

Take your time to prepare. You'll do great.
All the Best