There is a hadith with such a meaning:
يجيء الناكح يده يوم القيامة ويده حبلى
The one who masturbates with his hand will come on the Day of Judgement and his hand shall be pregnant
— Shu'ab al-Eemaan
It is weak.
Allah the Almighty is all-forgiving, there isn’t a sin he will not forgive if you repent for that sin. The hadith you mentioned is non-existent and is spread to make people scared. But remember Allah and if you were to die whilst masturbating.
It's always difficult to say that a certain hadith does not exist but it is quite certain that there is no sahih or Hasan hadith like that because the teaching that masturbation is haram is only based on the interpretation of Al-Muminun [23:5-7] 
Yes, Allah will forgive you once you repent with sincerity and work towards not repeating the sin.
I'm not sure of your exact age but assume you have achieved puberty. So if you are financially & emotionally capable, it is recommended that you get married.
Alternately, try to fast often, as it increases your taqwa and keeps you away from fitnah.