法律谘詢：關於共同購置的房產問題

跟前男友一起購置了房產，房產證和房貸上是兩個人的名字，稱為‘joint tenancy'.有法律網站上說：The Joint Tenancy means that ‘the co-owners do not have particular shares in the property; they own the whole thing together. Each has a right to live in and use the property (if they are a beneficial owner), during their lifetime. When one of the owners dies, the property becomes the possession of the other owner(s). If there is only one joint tenant left, he or she becomes outright owner of the property. Because no joint owner has a defined share, their interest in the property does not become part of their estate when the die, but simply disappears'.（http://www.thompsons.law.co.uk/ltext/fsfam004.htm#two_types_joint_ownership）

現在我想放棄這個房子的一半產權，不知道我以前交的房貸能不能算作投資要回來？是不是在居住期間（隻有三個月）要交房租呢，如果要交，交多少呢? 我能不能強迫對方賣房呢？哪種方案對我來講最有利呢？

多謝！