Legal Question in Real Estate Law in California

Your landlord is wrong; changing your name doesn't void contracts signed with the prior name. Therefore, "breaking" your lease would result in a potential claim for damages from the landlord. However, if your landlord says the lease is void, that suggests he/she may want to get out of said lease, so I'd suggest you consider getting together with him/her for a friendly, cool-headed negotiation to see if you can both achieve what you want, keeping in mind that your name change didn't affect the lease validity.