Assault & Battery: Assault Causing Bodily Harm Sentences

My question involves criminal law for the state of: Assault causing bodily harm.

Hello, i am an 18 year old university student in nova scotia, Canada. Always a good student, helpful and have never had so much as a speeding ticket before. The other night outside the campus bar i was grabbed and pushed around. I eventually hit my aggressor once and knocked him down. When i seen he was knocked to the ground and no longer a threat i ran back to my residence, when i figured it safe me and a friend went over to check on the guy in his residence and see if he was ok, upon arrival we were informed he was in the hospital, the next day he had to get surgery because he had a shattered cheek bone and had 4 plates placed in his face. That day i was arrested by the police and informed the aggressor was pressing charges " assault causing bodily harm or assault with a deadly weapon ". I am meeting with a lawyer this friday, and my court date is jan 24th, and have yet to give my statement until i go over it with my lawyer. I would just like to know the gravity of this charge, what a possibly fine/punishment will be for my first offence if found guilty. After surgery he was completely fine this happened 10 days ago and now he is 95% back to normal just small bruising / swelling and there wont be any permanent damage.

Both me and the other person were under the influence of alcohol.
I was alone in a group of all his friends, so i have no one who will be my witness and he possibly has his friends to say what ever he wants them too.
Before that night i have never so much as seen the other guy before, but me and his best friend do not get along so im assuming he grabbed me for that reason.

Thank you very much for the help.

Also if i am convicted, what are some possible punishments i will receive and is there a possibility of this getting removed from my record because i am considering going into med school after here. I am a first year student at this university and he is a third.