REST API test - Logging response from the API

Hi,
I am trying to load test a REST API. The REST API is a public API and has few limits (listed below).
1) There is a limit on number of API requests (cumulative) per day
2) There is a limit on the size of request/response for every API request
3) There is a limit on the API processing time (cumulative) for a day

If any of these limits are violated, either a HTML page is returned or specific error codes are returned. In such case, I want to stop the test and find out the load that breaks the limits.

I tried SOAP UI and Load UI Pro for this testing.
a) SOAP UI:
- Created a REST API Test case using the API endpoint
- Generated load test for the REST request
- Set threads to 50 and strategy as simple`
b) Load UI:
- Fixed Rate Generator (Number of user 100)+ REST Runner + Output Log components were used and orchestration built
- Inspite of errors returned by the API, the tests continue and are shown as completed.

In both the cases, I am unable to check the response from API and stop based on specific condition. Is this something possible? Appreciate your support in this regard?

Thanks and Regards
Siva