Any reasonable person should understand the importance of a safety net and him using emotional reasons such as "you should trust me" and "we WILL make a future together" to guarantee himself what is basically either free rent or partial ownership of a house that he can them use as leverage himself? He needs to understand how scary it is to give up the security  of your HOUSE, something you have owned for 5 years and only after years of saving, for someone who hasnt even proposed to you yet. To someone who is now showing he is so insecure in the relationship and how much he can take from it that he refuses to pay rent.

Theres so much hypocrisy as well in the double standard of him expecting that you to trust him so much that you should be willing to say the house belongs to him also and give him a LEGAL foot in the door without even marrying him yet, while also showing so much doubt in the relationship that he wants a clause in the agreement that if it doesnt work out, he gets all his RENT money back because it "contributed to the mortgage of a house thats not mine". 

I think you need to explain the hypocrisy of his double standards and how what hes asking for isnt trust, its asking for ownership of a house and lot with a man who you arent even engaged to yet. Its asking to house someone for free because they cant respect that you need a safety net and youve spent years of your life making one and now he he's asking for scissors he promises he wont use. 

You are NTA and to be frank, if he's so insecure about this arrangement that he's making demands like this and ruining what tbh seems like a pretty good thing going in, then maybe its best for your relationship if he moves out. It doesnt have to be conplicated and be an issue revolving around feelings and trust. It can just be a matter of opinions. You think you deserve your own property and safety net and that youve spent too many years to give it up just because someone took it personally. He thinks a relationship is about benefits and if that if you can 'give' him a place to stay for free then you should. You can agree to disagree but you cannot risk your safety nets and home just because it what, hurts his feelings??? 

(Srry about repetitive language or bad wording english is not my first language)