You are not a tenant. At best you have a personal licence to reside.
As the joint beneficial owner and joint mortgagee her right is to apply to the Court for the sale of the property. Whilst your partner has been paying the mortgage this will need to be taken into account in any equitable accounting. However, it will equally need to be taken into account that you two have had the benefit of the property and must pay an occupation rent. The two will generally cancel each other out.
She can't evict you as you are not there as a trespasser. Nor are you there as a tenant. You have a licence from your partner. She must take it up with him. She can be as difficult as she likes. She could make an application to have you both thrown out, but that is unlikely to get very far. The only thing she can do (and has an excellent chance of succeeding on) is getting an order for sale.