Is it obligatory to fast for 60 consecutive days, or just one day as expiation for breaking a compulsory fast, or is it considered breaking the fast out of forgetfulness, in the case of foreplay with one's wife during a state of purity (taharah) resulting in ejaculation?

You did well by breaking your fast when ill and fasting when able. It would have been better to consult a doctor. As long as you fasted that day and were not harmed, you were obliged to complete it. A man's fondling of his wife while fasting is permissible if he is certain there will be no annulment of the fast; otherwise, it is not. If ejaculation occurs, the fast is invalidated. If you intended to fondle her, confident that the fast would not be invalidated, there is no sin upon you, even if the fast was (subsequently) invalidated. However, if you anticipated ejaculation, you have sinned, and you must repent. Your fast has been invalidated by your ejaculation, and you must make up that day; there is no expiation required of you.