@Anja_SG sorry for the delay in response
1. As long as your husband retains US citizenship, he will be taxed by the USA on world income and be able to exclude foreign earned income ( up to a max amount that is indexed yearly ) as long he qualifies for a foreign tax home.
2. If you file jointly then giving up Green Card does not do anything for you -- you will still have your wrold income taxed by the USA. If you wish for the USDA not to tax your SG income, then your husband would have to file as Married Filing Separate ( MFS) or as Head of Household ( HoH ) , if you have child(ren) that he maintains a household for .
3. If you continue with the GC abandonment , you will have to file 8854 and this is where you will have some issues with the properties that you jointly hold/own. If you have already abandoned your GC, then you may have to gift your ownership(s) to your husband, to avoid complications of filing form 8854. Would strongly suggest consultation with tax attorney or tax professional familiar with Expatriation Tax ( IRC 877 ) and its mark-to-market regime. In prep. for this perhaps a read of the following may be useful :
Expatriation Tax | Internal Revenue Service (irs.gov)
Is there more I can do for you ?
Stay safe
