HELP! My sons father is taking me to court for FULL CUSTODY!!?

I am 22 year old single mother of a 2 year old boy, my sons father is 23 years old and we both have shared custody of our son but here is the problem.. He is taking me to court for FULL CUSTODY I got a knock on my door at around 11AM in the morning from his LITTLE SISTER giving me court papers and I didn't handle it very well so I broke down crying infront of her and asking her why she stated for me to ask her brother. The papers showed that he filed for court on me on MAY 12, But I got the papers MAY 31st !!! He gave it to me late notice and court was about 26 days away from that date, I have court on June 30th at 11AM. I live in Canada Toronto, Ontario. I breastfed my son for 5 months, I lived with my mother since my son was 1 years old and then got my own apartment after that but before that i was living with my mother and she was helping me with everything, I took my son to all his doctors appointments, I had him full time since he was 3 months old and after that his father had him for the weekends I was nice enough to do that for him, He NEVER PAYED CHILD SUPPORT only until we had an incident that happened on my sons birthday when I punched my sons father in the face because he said something horrible to me that I couldn't take in, him and his sister both forcefully took me out of the car (his sisters car) and tried driving off wiht my son in the car I called the police and the call turned out on me because him and sister stated i punched him in the face while she was driving and me and my son were in the back seat. The police asked them if they wanted to press charges on me and they said No, and they asked if my sons father was paying child support and he said no and they said he needs to start! I am not going to lie and say that did not happen it did but i appologized but because she told the police that they got childrens aid involved but the lady came to my house hold and she seen that my apartment was CLEAN there was food in the FRIDGE AND CUBBOARDS, and that my son was well taken care of. I am not rich I am on assistant since I WAS a full time mother. in December my sons father took my son to MEXICO he begged me and I told him no (reason because i felt my son was to young of age and i was afraid of all the sickness or dangers he can go through) he got his parents who reside in Mexico to call me and I said yes because they were begging for about an hour on the phone) I signed the papers for him to leave the country just to be nice. before that in October 2010 he automatically took my son from me full time and put him in daycare without my consent! and I ended up having him on the weekends ever since and still do. I missed some weekends but only because I am looking for work! I haven't found work yet but I am trying and I want my son to be with me Mon-Fri and his fathers to have him on the weekends I am a good mother there is no reason for me to not have my son, I do not do drugs or alcohol or believe in abuse! He has money I am on welfare how will I win this case my sons fathers girlfirend (that he cheated on me with when i was 7 and half months pregnant is on the daycare papers and she picks my son up from daycare. I don't work and my sons father lives with his sisters in a condo and works a 9-5 Job so I have no clue of why he wants my son full time I can have more time with my son as I do not work! he lied on the court papers and said my house is DIRTY, I have no FOOD, and that my hallway stinks of marijuana (my neighbors smoke alllllll daay) and stinks up the hallway. My house is CLEAN, and I do have food in the fridge I make sure to put breakfast lunch and dinner on the table at ALL times when my son is with me! I spoke with my sons father and he even appologized to me for assuming that i do not have food and all that stuff but he said he wants mondays to fridays and that he wants me to have weekends, but on the court papers he put SOLE CUSTODY and said I can only have SUPERVISED VISITS as if I am some crack head or something! Even my mother had to tell him he is in the wrong but he is doing this for his girlfirend and his sisters because if he was doing what was best for his son he would know mom is best for fulltime care giver! he even put the incident of when I punched him in his face on the court papers !! I spoke with him the other day and he said he would not take me to court if we can have a decent agreement so instead of going looking for a lawyer I left it alone, but he told me just 2 days ago that he will be taking me and that he will see me in court and that he has a GOOD lawyer and that I do too and I told him I don't have a lawyer and he said oh well see you there and hanged up on me ! Court is on thursday.........I have NO Lawyer, No nothing.. the onlly thing I have is witness what am I to do and I haven't seen my son in 2 weeks he is KEEPING MY SON FROM ME! I feel like breaking down what am I to do what can I do they are going to take everything from me!