Dividing property

I have been in a common law relationship for over three years and we have a child together. We also bought a townhouse together where I paid a substantial amount towards the downpayment of the home and he paid nothing. This was with the understanding that he would be be the financial provider so that I would be able to stay at home and take care of our child. In the begining I was getting a small amount from EI and was able to contribute by paying my own expenses etc... After that had expired he continued paying the mortgage for the home and utilities but has refused to pay any of my bills. I have been managing with help from my family. I have since started my business at home which is very slow starting up and as such does not provide a lot of income. I would like a separation as I feel very cheated by this individual. I not only paid the whole amount for the downpayment but also paid a large sum towards his credit card which had a high balance with the understanding that he would be able to better support us. He has a drinking problem and I have had to call the cops out to our home a number of times. I have stayed in this relationship for my daughters sake as everytime I bring up separation he threatens he will fight for full custody. While I know that won't happen I am afraid for him even to have shared custody for a number of reasons. I would like to know how much of an argument I will have to get back my money that I paid towards the purchase of the home. I have kept receipts and the money was a gift from my mother. He had assured me that the downpayment on the home and the money I paid on his credit card would all be reimbursed to me on the sale of the home.