breach on contract to sell made?

a 400 sq. land owned by one person but is divided into small parts with diff. tenants..i acquire a piece when 1 of the tenants decided not to purchase his, a contract to sell was issued and signed by the land owner representative and me but after a week said tenant change his mind and will now purchase the land but must be given 1 month to gather the money...according to the owner she has no choice but to terminate our contract since priority is given to the tenant and that it will only be given to me if the tenant cannot produce the amount on the promise date. is that right? isnt the contract signed by both of us binding? can it be consider as breach of contract? what is my right to the land if ever?