Unlawful Detainer Filed Against Me as Buyer Under Notarized Contract to Sell – How to Secure Full Refund?

Hello,
I’m seeking guidance regarding a property dispute. Here’s the situation:
I entered into a notarized Contract to Sell for a house worth ₱7.7 million.
I have already paid approximately ₱4.8 million to the seller.
The contract includes a clause stating that if the balance is not fully paid, the buyer shall vacate the property, and the seller must return all amounts paid.
I have been granted possession of the property under the contract.
Recently, the seller filed an unlawful detainer case against me, claiming I have no right to occupy the property.
I am represented by a lawyer, and we are considering filing a counterclaim for specific performance to protect my payments.
My goal is to secure a 100% refund of all amounts paid (₱4.6M) before any eviction occurs, based on the clause in the notarized contract.
My questions:
What is the best legal approach to enforce the refund under these circumstances?
How does filing a counterclaim for specific performance interact with the unlawful detainer case?
Are there any risks or pitfalls I should be aware of to avoid losing leverage or money?
Any advice or insights on the legal strategy to ensure full refund would be greatly appreciated.
Thank you.