Do I have any legal right to this house?

Location: Colorado

My future ex and I bought a house last year. It was paid for in cash. My partner’s mother wire transferred him the majority of the money to his checking account and then he paid some of the closing costs himself. We are listed as “joint tenants” on the deed.

We have been together for 6 years but are not married. Colorado is a common law state so there is potentially an argument to be made that we are in a common law marriage.

Ignoring whether or not it’s fair or morally correct or whatever since I did not contribute financially to this, do I have any legal right to this house? And should I expect a lengthy, costly court battle if so?