Do I have a case if I ate fried roach and how much is it worth?

There is no science to valuation. I'd play up your mental distress, its physical manifestations and treatment, and the revulsion of the situation. I'd ask for $10,000 which is the limit for which you can sue in Small Claims Court. You also may want to report the incident to your County Health Dept. as the roach likely came into the food there at the restaurant.

Yes, the restaurant was negligent in serving you a cockroach, but you seem to have greatly over reacted. You could probably get them to pay for an initial ER visit and maybe a hundred dollars or so for emotional distress, but few people are going to believe that you really needed mental treatments. A personal injury defendant takes the plaintiff as they are, including a plaintiff who is more sensitive than a normal person, but a trier of fact will base their judgment as to damages based upon what they feel is reasonable. I doubt anyone will feel that a need for psychology treatment is really necessary for such a relatively minor event. It is not worth hiring an attorney, and none would probably take the case, except if you paid they an hourly fee and they merely write a demand letter. See what you can get by yourself from the restaurant, but suing will not be worthwhile.

Every claim or law suit has two basic elements: Liability (fault) and damages (how much). Many times a person may have a good claim but the damages are insufficient to interest a lawyer in taking your case. If the damages are modest you may wish to sue in Small Claims Court, where no lawyers are allowed and the damages are limited to $10,000.