Confusion about "Past Real Conditional"
Solution 1:
The first part of that sentence sketches a condition ("if..."), the second part the action. There is no reason to assume that "that" refers to both the condition and action. We do not know anything about the frequency of that condition. Moreover, if it did refer to the whole sentence, then there was no reason to make a condition in the first place; one would simply write: I usually went out with my friends. I can't do that anymore.