Will I still get money for my house? Uk

So long story short, me and my ex bought a house together in 2024 and we are both on the mortgage 50-50. We would pay all the bills and the mortgage from a joint bank account in both our names. Ahe has always earnt more than me in wages but everything has always come from the joint. We decided because she has a son (not mine) that I will move back into my parents and she will stay in the house paying all the bills from the joint account and I will just not pay anything because im not living there. We agreed when she does sell the house I will get 50% of what the house is worth the day I move out not when she sells it

Now all of this agreements are in verbal and nothing on paper or official and we are just trusting each other etc - my question is this, if in 5+ years she decides to sell the house, can she stop me getting my bit if she proves I havent been paying towards it at all? Can I just argue back that shes paying me my half as rent etc?

I know im not going to be financially better than before buying the house but will I be left with nothing or no matter what, ill still have 50% of the sale?

Im in no rush for the money now so I dont mind how long she lives here for I just want to make sure I still get what I put in at the start

Oh we are not married and never been - if thats important