To understand the book of Job, you read the first two chapters and the last five. Between those chapters is the infallible record of what fallible men said, including Job. While he was godly, not everything he said and felt was correct.
In the immediate aftermath of what occurred, we read, “In all this Job sinned not, nor charged God foolishly.” (Job 1:22). After this, however, the reality of what has taken place deepens his grief. Considering he lost his wealth, health, and children, Job wishes he had never lived. That was wrong, but hardly surprising.
However, I don’t think his escapism necessitates he was suicidal. In Job 6:8-11 we see he still recognized God’s right to choose the time of his death, saying, “…that it would please God to destroy me; that he would let loose his hand, and cut me off!” His desire to be brought to death by the Lord, is not the same as being suicidal.
Be that as it may, he was wrong to curse his day, and God does address him later in the book to humble him.