Under Australian family law when a de facto relationship ends after 2 or more years, the parties property should be divided in essentially the same way as if a marriage had broken up.
Contrary to popular belief, however, the parties to a broken relationship are not entitled to an even share, rather the law provides that each party is entitled to a fair share of the relationship asset pool (all assets owned by either party and including superannuation) having regard to the contributions that each party has made and then adjusting for special factors such as the impact of children or where a party has serious health issues which will impact their ability to support themselves.
So your greater contributions to the to the house you are living in will be factors very much in your favour when determining a property split, though the court will not consider this asset in isolation, but will also consider the total asset pool, which includes your ex's property that she brought to the table, which is a factor in her favour when deciding on a fair apportionment. Your health issues may or may not be considered a significant factor depending on how long term they are and the extent to which they affect you.
Only a fully briefed lawyer familiar with the detailed circumstances of your history as a couple and your current financial and health circumstances can give you a firm estimate as to your actual entitlement, but based on what you say it would seem likely you will receive something less than half the total asset pool (which includes the property your partner brought into the relationship, but which may ultimately reflect a greater share of the property you are currently living in.
I trust the above assists your understanding.
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