Sale of 2+ unit property used as STR but also as primary residenc

[Theodore Smith]

Pretty sure I need some local Real Estate CPA tax advice, but thought I would post real quick to get any thoughts. Planning on reaching out to some CPA's next week.

Some Facts-

Purchased Property 07/26/2019

Price - $425,000

Current Basis - ~$515,000

Est Sale Price - 1,300,000

When we purchased property there were 2 houses on property. We added an additional home along with a large barn. So, there are now 3 houses and a large barn. From Jun through Sep, we STR the 3 houses and we live in the barn. Oct through May we live in one of the houses. This is our primary residence as we do not own any other property.

We have filed taxes in in 2019-2021 as a Qualified Joint Venture since we are a husband and wife general partnership. So, in essence, we treat the income & expenses as 3 separate units and we split the income & expenses 50/50 for the QJV and file the according Sch E's. No Sch C.  Basically a sole proprietor.

My question really comes down to what our, if any, long term capital gain exemption on a home sale will be? I understand there is a max of $500,000 for married filing jointly. I just can't get my head around if we qualify. We have lived on the property as a primary residence for over 2 of the last 5 years. But obviously we have only lived in one of the homes on the property for the required 2+ years not each of the homes. We have not used this exemption in the past. But we have also used this property as STR income.

Do we get the entire $500k exemption because this is our primary residence and we've lived on it for 2+ years?

Or do we not since it's used as a STR income investment?

Or, my guess more likely, it's some combination of the two? Just have a feeling it's a ridiculously complicated formula to try and figure out what that might be.

Thanks.