I NEED HELP TO BREAK MY HYMEN!!

Hello, Im Monse, Im 23 years old. I have been in a long-lasting, committed  relationship  with a girl  for 7 years. Yeap, since  middle school!!.  I love her so much, really,  and we  have a normal sex live. However, since ive been with her since very early in my life , I havent had neither the opportunity, nor the desire, to have sex with a  man.  But I   constantly fantasized  with vaginal penetration. We have tried  with  few  fingers,  four is the maximun, I think. Recently, I  got a new dildo, thinking that, as I havent experienced any discomfort with the fingers, on the contrary, I wasnt  going to have any problem with the dildo. But, oh my! I was wrong. I can  get maybe only the tip of the dammed thing, even when  im completely aroused and helped  by the girlfriend. So  i think i have my hymen  intact still.  We really want to break it, so  I can  experienced this I want so badly. But I have  read many  things in Internet about  rupturing  your vaginal  wall, so I figured that maybe, if I pushed to hard, I can hurt myself. Idont want that. Please Help m, Im desperate. I want to know,  if maybe theres a right way of using a dildo the first time to make sure it is safe and pleasurable.  Thnks! :)

PSD: Im sorry for my english, its not my first tongue!