Correct spelling, explanation: in English, there is a rule that suggests that the consonant is double when it occurs in a syllable that is stressed. For example, in words such as referred, committed, admitted, etc., we write the double consonant because these phrases end in 1 vowel + 1 consonant and the final syllable is stressed. However, in the word visited the syllable vi is, not sit and you do not need to double the consonant. Therefore, the form visited is correct, not visitted.

Definition of visited:
verb, the regular past form of verb visit that means to go to meet a person or see a place,
When we were in Varna, we visited several places of interest.
They visited an art gallery while they were in London.

Phrases with visited:
visit something on/upon someone – inflict harm on someone or a place; cause damage or harmful event,
Two years ago famine visited this country and many people were forced to flee.
(old use) inflict a penalty on somebody,
Children sometimes suffer because the sins of their parents are visited upon them.

Incorrect spelling, explanation: visitted is an incorrect form of past participle verb because there is a rule which says that we double the consonant in a stressed syllable. The syllable sit is not stressed so we should not write two letters t. As a result, the form visitted is incorrect.

Incorrect spelling

Incorrect spelling

Incorrect spelling