What can actually happen to me in a civil dispute over property? Need lawyer advice

So as the title says, I need some professional advice on this.

Over the last 18 months, my ex and I broke up. It wasn’t a nice break up, she tried to screw me over jn all avenues. We had property together on both our names 50/50 share, with 50/50 responsibility to pay the bond. We had a separate contract set up stating everything is 50/50. The house is in my home town so when we broke up I obviously wanted to keep the place and buy her out.

When it came time to come to an agreement on the amount I need to buy her out on, we obviously had to get an evaluation to accommodate for property growth. Now, in the contract it states that if we do not come to an agreement within 30 days, we need to sell and split the funds.
But she, knowing that I didn’t want to sell and keep it, decided to jack up the price with R400k over value.

It was a long fight back then and I knew that they were just pushing me into a corner I couldn’t back out of so I verbally agreed to their sell price.

Then I made a clause saying that I will pay her a lump sum of lets say R1m while there is still R400k outstanding, and then once the property is in my name, I will pay out the remaining R400k.

A sale agreement was drawn up with this clause, I paid the lump sum to the transferring attorneys, the house then was transferred into my name.
Now I owe her the remaining R400k.

But, for almost a year she didnt pay her side of the bond and I had to pay it solo. This was her essentially breaking contract as we both had 50/50 financial responsibility. I also recently discovered she had cheated on me so obviously I am furious and now feel that I dont want to pay out the R400k.
Not because of emotion, but purely because of her not paying the bond and also because she jacked up the price of the property evaluation.

Now my question is, even if her lawyer gets the instruction to litigate this situation that I owe her R400k, what can actually happen to me? And how long will the court even take to process this? Also will it be a valid case considering my case against her?