法律咨询：关于共同购置的房产问题

跟前男友一起购置了房产，房产证和房贷上是两个人的名字，称为‘joint tenancy'.有法律网站上说：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）

现在我想放弃这个房子的一半产权，不知道我以前交的房贷能不能算作投资要回来？是不是在居住期间（只有三个月）要交房租呢，如果要交，交多少呢? 我能不能强迫对方卖房呢？哪种方案对我来讲最有利呢？

多谢！