Answer:
former felicity, solitary, desolation, unjustly
Step-by-step explanation:
The passage is something of a lament as it contemplates the justness or unjustness of what happens in life. The author is aware that he could have been quite well-off in another life, but that a series of interventions by what he describes as heaven kept him from reaching that path.
Former felicity and unjustly reflect the state of mind of the author. Desolation and solitary reflect the experiences he lives and how that impact pervades his existence even today.