Do you think this was deliberate and should I seek legal help?

Refrig. I believe someone is coming in and out of my apt. I put my pot of food in the refrigerator, I paid close attention to the top, I wiped it off, when I came home I went to take it out and there were roaches on the lid. I have left the pot out now for 24 hours still this morning there are no roaches on this same pot of food. I have had a feeling that someone was coming in and out of my apartment, but nothing as definitive as this incident.
YES GIRL YES YES YES PUT A LOCK ON YORU DOOR AND CALL THE POLICE ANS I THINK YOU CAN ASK THEM TO WATCH YOUR HOUSE AT NIGHT FOR ONE NIGHTE HIDDEN SO THEY CAN SEE IF WUM1 IS GOING IN YOUR HOUSE. thats nasty about the roaches.
You might need psychiatric help, but you don't need legal help.

Change the locks on your doors and don't give anyone else a key.
I don't know how bugs on your food determine whether someone was in your apartment. Before you jump to conclusions put a thin strip of transparent tape on the edge of your door, either near the bottom or top, where it won't be seen by a casual observer. If someone opens the door the tape will break and you will know someone has entered.

A lot of landlords have clauses in their leases that say they can enter your apartment at anytime (sometimes they need to call an hour ahead incase you are there, but if you are not they can still come in.) in order to show a 'typical' apartment to a customer, make repairs, etc...
Make sure you have definitave proof and you have all your ducks in a row before you start pointing fingers.
You should call an exterminator for the roaches.

Otherwise, sounds like you should seek psychiatric counselling.