No, that's not possible. If you will *not* be filing your 2018 return as married filing joint (and you won't if your legal status is not married on Dec 31 of 2018) then you will each need to start a completely new account. Both of you will need a printout of the 2017 joint return, because you will each be asked for information from that 2017 joint return, for your first 2018 "single" or "head of household" (if you qualify for HOH) return.
Under no circumstances should either of you use the old account and import "anything" from the 2017 joint return. If you do, chances are extremely high that your 2018 return will be wrong.
