Sure! I'm not a native Dutch speaker, but I'll do my best.
For one, you were trying to use blij as a verb, but blij is an adjective. You wouldn't say "ik blij van..." but rather "ik ben blij dat..." I am glad that...
So the question would be: Why are you so happy? Waarom ben je zo blij?
Next you were trying to use gescheiden as a noun: je/jouw gescheiden, your divorce. But gescheiden is an adjective: We zijn gescheiden. We are divorced. Ik ben gescheiden. I am divorced. Je bent gescheiden. You are divorced.
In English you might ask, "Why are you so glad to be divorced?" But in Dutch it's more like "Why are you so glad that you're divorced?" Waarom ben je zo blij dat je gescheiden bent?
"Waarom blij je van je gescheiden" sounds like you're asking, "Why glad you from your divorced?"
Hope this helps!
There is no specific verb for blij which is why you need to use a form of the verb zijn (to be): Ik ben blij. I can't really explain how to tell them apart. It's just something you have to learn as you progress with the language. The simplest explanation is that a verb expresses an action (rennen: ik ren de trap op), a state of being (zijn: ik ben jaloers), ownership (hebben: ik heb een auto), etc., while an adjective describes someone or something: een blije baby; hij is blij; zij is blij. In English you say: I am hungry (verb + adjective). Hungry describes your state of being. While in Dutch you say: ik heb honger (verb + noun). Honger is something that you possess: I have hunger.