Any suggestions as a tenant with a strict landlord?

I used furnished finder to rent a condo 8 weeks ago, signed a contract until end of May. We were house hunting and now closing on a house. We’ve had a lot of ups and downs, deals going through and being pushed to close early and all these things. My landlord was a little flexible at first saying if she found someone to rent in May, we could break the contract but then a potential lead wanted a video of the condo while we are living there and I said no, okay let’s just keep the contract- the first house went through anyways and I didn’t think we’d find another house so soon but we did. And now that we are closing on a house, I’ve gotten pushback from the seller, realtor and lender about trying to extend closing so we are closing this month. I asked my landlord if that’s something they can be open to again and they said nope not doing this back and forth. So basically we are moving out on the 30th and paying May rent while we won’t live there. Do I need to give him notice now that is something we will do? I asked to prorate if we stayed a little into May, and they said no. It was my mistake thinking furnished finder landlords were more lenient - only because my sister is also a landlord on there and can’t fathom this. So I know we signed a contact and will deal with it.