Here's a not so gentle slap. Before you have a conversation with him you need to have a conversation with yourself. This dynamic didn't sort of just happen, you enabled it by not having enough confidence or respect for yourself to stand up to someone whose taking the obvious piss. Not only is he is a piss taker, he's pretty slick with it too, see how he stopped the conversation by suggesting you talk rather than text, yet conveniently forgets to restart the conversation. He should write the 'Cocklodgers Guide'.
You need to start judging him by his actions and not by his words, he talks a good talk, like offering to contribute (his incredulity at you asking him to make good on his fake offer, is testimony to him knowing that the offer was nothing more than just talk).
Labelling him as tight, rather than mean is just an excuse for you not to accept him for who he is (I'm sure there's more to him than being a cocklodger but it is particularly significant character trait). His gross sense of entitlement is not just confined to money, the man has semi moved in with you without discussing it, why? Because he believes he's entitled to. I can only imagine how he would manipulate you into putting more capital into a shared home, whilst expecting an equal share.
Subsidising him when he is the greater earner and has less costs is madness and says a lot, not just about him but you as well.
What do you want from a relationship? How do you expect to be treated and more importantly, what are you going to do if those expectations aren't met. Relationship dynamics require contributions from both parties and part of your contribution to your relationship dynamic, is doormat. Own your contribution and if you don't like it, change it because let's be clear, he behaves this way partly because he knows you'll take it. You are an equal shareholder in your relationship, so start acting like it.
Despite all the evidence to the contrary, it was a complete shock when I realised that my Ex didn't respect me. I made excuses for poor behaviour and treated poor behaviour as isolated incidents, winch blinded me to the inevitable pattern that ensued. The truth is, I was selective about what I wanted to believe about him because I prized having a relationship, over the quality of the relationship.