Not sure if it’s quite what you’re looking for but the first thing that comes to mind for me is Ceph. It’s not exactly a service in and of itself but it is self hostable/open source. I currently have a cluster set up across 3 machines with 87 TiB total space and a Ceph Filesystem and thought it was relatively easy to set up (I’d recommend first doing so in a virtual environment to get your bearings if possible, though). Said filesystem is set to make 3 replicas (1 on each machine) of any data written to it and I use Unison to sync files between local storage and the cluster (such that the whole setup is analogous to Windows/Onedrive or MacOS/iCloud). I also plan on setting up a node at my parents’ house and making a new replication rule for that. As they live in a different state than me, this would amount to having hot offsite backups (for both me and them). Finally, while I haven’t seen it done in practice, in theory, multiple Ceph admins may be able to configure a multi-site setup where they could trade some space on their own clusters with each other for a sort of community based storage pool/hot offsite backups (like a community ran version of Google Drive or similar where the buy-in could be some of your own storage space or money). However, it’s important to note that while communications are encrypted and the storage drives can be encrypted as part of setup and operation, any data written to a cluster is not automatically encrypted and if one wants privacy, said data would need to be encrypted separately before writing it to a community cluster.
Your post doesn’t indicate your level of opsec, the country you live in, or your abuser’s technical understanding of computing machinery and security. Something important to be aware of (if you’re not already) is depending on where you’re posting from and what your abuser has access to, a post like yours–or following any of the links below–without taking appropriate precautions could put you in (further) danger.
The first thing that should be established (if you don’t already have one) is a threat model–consider things like: what are your abuser’s capabilities? (what do they know?, what can they access?, etc); what do you want to keep from them? (ie your online activities, especially as they relate to getting out of your situation if that is your goal); what controls/defenses can you use to keep yourself safe, prevent info discovery, mitigate harm, etc? How you can safely proceed depends on your threat model, which depends on your own unique circumstances.
Here are a few links, but please proceed carefully (if you don’t want to follow them for safety reasons, feel free to ask questions here):
A decent repo of resources to use computing machinery privately and securely: https://www.techlore.tech/resources
I’m not familiar with resources for abuse, but I found this from a relatively quick search: https://www.thehotline.org/get-help/domestic-violence-local-resources/
For psychological help (therapy, counseling, etc): https://www.psychologytoday.com/us
If the above is not the type of response you were seeking (or you were already aware of it all), feel free to disregard it. (I understand at least some of the potential implications of this post being in a cybersecurity community on a cybersecurity Lemmy instance, but I didn’t want to assume just in case.) Regardless, I hear you. Your situation sounds awful. (If you just wanted to effectively shout into the void for some type of release, feel free to ignore this entire response. Finally, just in case anyone is wondering: the reason I replied here instead of privately is in the case resources/info are desired, others can provide better links/info and/or correct anything that’s wrong/dubious–I’m just a computer nerd with questionable social skills who wasn’t sure if/how to respond 😅…)