Are you married or common law?
If married, it is the mat home and split 50/50.
If common law, there is no mat home, but you state "we purchased". Did both of you pay into the house? If so, you both have a right to amount paid in.
If common law, if the home is in your name then it is your home, although you may owe her for any investment she made in it.
If married, you both have equal right to possession of the home.
You have one child living with you full time and two children over 50%. You have cause to seek exclusive possession of the home and have her out. The cause would be that the children have a right to live in their home and not have their lives disrupted unnecessarily. This trumps either of you or your ex's right to possession. To put it another way, if it is the mat home and your rights to possession are equal, then having the children most of the time with you gives you a stronger claim.
Does your ex work, have any income etc?
And child support paid is calculated this way: She pays you the full amount for the one child who lives with you. For the other two children, if they are with you less than 60%, then it would be shared custody and you and the ex would pay each other. So the higher earner has the other amount deducted.
So take what she pays you and deduct that from what you pay her.
If she doesn't work, then she should be imputed at least a full-time minimum wage salary and support should be based on that.
You should file with the Federal government immediately to indicate the children living with you, the exact amount of days. You should be receiving the full CCTB for one child and half the CCTB for the other two. You should also be able to claim them as dependants and claim for any sports and summer camps. It will also affect possible GST/HST refunds. It is important to file with the CRA, there is a form you can download on their website.
If you earn too much to receive any CCTB or GST benefits, you still should file this so that you establish with the government that you and your ex are separated and that you have shared physical custody of two children, and sole physical custody of one.
In Ontario, having a child live with you is refered to as "ACCESS" and legal decision making is referred to as "CUSTODY". According to the Children's Law Reform Act, you automatically have JOINT LEGAL DECISION MAKING (CUSTODY) if the children reside with you both, after separating. This will remain true unless or until there is a court order stating differently, or there is a signed legal agreement between the two of you.
Spend as much time with the hockey and other sports, at the school, talk with the teachers, take them to the dentist and doctor's appointments, and make sure all of these professionals HAVE YOUR ADDRESS listed as the children's residence. Play fair and note that the mother's address is the secondary residence of two children, but describe your apartment in all documents as the PRIMARY RESIDENCE.
Above all make sure you protect your time with the kids, don't let the mum take them more than 50%, avoid arguments and confrontations, let things settle down and establish a routine for the kids.
Once you have them living with you for 6 months then STATUS QUO sets in and it is very difficult for the mum to challenge you and try to take full custody. Avoid games, avoid talking to her on the phone, avoid arguments, you have NOTHING to prove to her, just be a good dad and provide a home for the kids.
Speak to a lawyer soon, you can get a free hour consultation by calling the Law Society of Upper Canada.
Get the most out of your consultation, have a lot of organized notes that detail your finances and the details of the kids and the length of marriage and ownership status of the house. Have a list of questions ready. Don't let the lawyer just talk talk talk, ask your questions and write down the answers. Then rest and read and think before you act.