I think your translation is roughly correct but there appear to have been some misunderstanding of the grammar:
に is not a particle in this case: it is used for making 常{つね}に an adverb.
と has several uses as a particle (in addition to being “and”): It can be used when an action is done “with” a person where it would be used like 先生{せんせい}と食{た}べた “I ate with [my] teacher”. It is also used to mark quotes as for ~と言{い}う “I say that...” and ~と思{おも}う “I think that...”. I’m not familiar with this verb but と could also be marking a quote here.
いた is the plain-past form of いる/います “to exist” (animate) objects. It it used with the て-form of verbs (some verbs use で) for ongoing (present participle) or habitual (regularly occurring) actions. In this case it is a habitual action performed in the past.
私{わたし}はその人{その}を常{つね}に先生{せんせい}と呼{よ}んでいた。
I used to always call that person “my teacher/mentor” (regularly)
While there are some good grammatical examples in this sentence, many of these have been covered in previous questions. Please use more specific grammatical questions in the future.
こんでいた
-- ? It's [呼]{よ}んでいた, no? It's from 漱石's こころ, right?