On top of that watch me speak to a lawyer and find out your wrong. Your probably stating your opinion not facts.
Right... Because we're all 30 year olds posting from our parents basements in our underwear.
Getting answers different from what you'd like to hear doesn't mean that the answers are wrong.
OP there is nothing the legal system is going too do as to our belief that your ex partner should contribute more due to presence of their adult child . I would think it reasonable that the presence of 3d adult be factored into all costs but this was never part of the deal you struck and it is too late now as you post it.
Caution ...that 3d person is most likely a tenant and tenants have piles of rights , and it may be most daunting to get the place sold promptly with a tenant ensconce in there and failing to move out and (if ) your ex failing to take due process steps to implement same .
Hush HRZ! You're not saying what OP wants to hear... You must be an enabler.
Or, like the rest of us, posting from a relative's basement in our underwear. (I'll add a fluffy robe and bunny slippers - it was nippy this morning.)
About the only solution I can see for OP continuing to live there is to essentially split the place into 2 units. Separate fridges, separate cable bill.... eventually separate electric and water bills...
I see the 30 year old making it difficult to market this house. (We have one of those cases in my neighborhood... the real estate photos are unintentionally hilarious - the one in focus have dirty garbage cans in rooms.)