Your options are that their Dad takes them, someone else takes them and claims kinship payments, or they go into temporary foster care. There isn't another option.
If their Dad takes them, that can be a private arrangement between you, but it sounds like he's reluctant.
Someone else taking them would require you to have parents or in-laws, or close friends, who were happy to take them on. Again this could be private, but if social services were involved, they could claim kinship payments for the time that they have them. I believe this would stop any child-related payments that you get, if that's relevant.
Temporary foster care would be a last resort, and social services would approach Dad first. There are lovely foster homes, though, I've personal experience of being inside several. It's very unlikely that they'd only take some of your children - it's far more likely they'd all be placed in temporary foster care, and then when you're assessed as being well enough to care for them again, they'd return to you (unless there were reasons that this wasn't appropriate). Depending on how long they were in foster care, it may be a slower return - such as weekly visits, and then every other day, and then daily, and then back to you but with daily visits from the foster parents, and then every other day, etc.
Realistically only the first or the last option is going to give you a break, and in either case, it's probably going to need to be all of your children, or you're not really going to get a break and you may cause some resentment/hurt between your children.