Termination for insubordination

Dear sir, I used to for an International school in Bangalore from 2014. My designation is an administration officer in one of their branch for children between 2- 6 years. We have a Head of centre and I report to her and she intern reports to head of school sitting in main school. we have a very strick policy of no men allowed inside the campus. In the month of July while the school was closed for children but office will be opened for parents visits. On my random checks once back fro leave noticed that there was variance in support staff check out time and when questioned they said they were following the HOC instructions and one of the days she has sent them way too early , when there was workers in the campus because she had a personal visitor. She has received him personally at the gate and there was no entry made in the security registers at the gate and ahs asked the maids to leave immediately, has ordered lunch for self and guest and both of them walk out of the campus at 3.06 while he entered at 1.30 pm.as per CCTV. No entry made while going out as well. As a part of security breach sent an email to HOC to clarify the situation, another lady supposed to be the coordinator replies claiming she was aware of the visitor and that I need to concentrate on training the security and not this. When I questioned her further that this is a part of my job, they abused me for making personal insinuation. While the case was forwarded by them to head of school and she called me and spoke to me very nicely and when asked her if men like this are allowed inside the campus she accepted no but in her case she had got him for her own security as there were vendors working. I replied she could made the maids stay back there was no necessity to send them early. She however convinced me and advised me next time to sort the issues over call than mail. Later in the evening at 5.00 I get a termination notice reason being I suspected my HOC actions and clear case of insubordinations. There were few mails where they had praised me for my good work , all of them were hacked and deleted as it was my company account. But I have a copy of the mail and all the conversations over the calls was recorded in my mobile. Please advice can I sue my company for terminating me being loyal and truthful.