Laid off within 5 months from first Job

I got laid off within 5 months of joining the company as a Fresher it was my first job during PG I was under training for 1-1.5 months and got shifted to the actual work department due to requirements in that department. I was under probation for 3 months but the period extended for 1 month due to PG exams. I eventually worked with determination as it was my first job I even worked on weekends and sacrificed my health sleep for that job yes I accept i made some mistakes and was not able to adhere to the tight deadlines sometimes. My manager used to call me and used to tell me that he is not seeing any improvement in my performance also said or else he had to escalate this matter to the senior managers. I was giving my best working late nights even skipping my meals to finish the work on time also the deadlines got tighter and tighter. When the probation period got over i received a call from hr telling we have to part ways the time taken for completing a task is longer the performance was not up to the mark. she also told if you don't resign you'll be blacklisted and would face consequences. After listening to this I was heartbroken despite working with honesty and determination I was not confirmed. My peers who joined the organization with me got confirmed for that position. I am looking for another job and facing questions like why you left the previous job as a fresher I have no idea what to say. I am not sure about the next job i don't want to face this situation again it destroys mental peace, confidence and develops self doubt what should I do I am vulnerable......