First point, sorry if this sounds harsh - you have 5 children so I don’t think blaming him for stopping you having any more children is fair or valid. Look at some other threads regarding infertility and count yourself lucky you have been fortunate enough to have 5.
Second point, if you have 5 children, I’m guessing you have been married for a while? Woe I understand your hurt on this topic since you are catholic and this sort of thing is not allowed in the catholic faith - I am finding it hard to understand why it would be the reason to stop you loving your husband and thinking if separation? Is there something else at play here? Maybe other reasons which have built up over time and this is just the last straw.
I’m still learning the catholic faith so I don’t know if this is true, but since your husband is Protestant, this sort of thing is allowed - would it mean you were also committing a sin even though you have not improved? Surely it would just fall onto your husband? (From the catholics perspective).
I think there is more at play here and you need to try and have open communications with your husband and ask why he needs to go through with the procedure and not just through NFP. Maybe he thinks you are being greedy? Maybe he is happy with the children you already have, doesn’t want anymore? Maybe it’s a way for him to make sure there is no other children? Women can be very sneaky with birth control even if it is via NFP. I’m not saying you have a dishonest nature, but I know how being broody feels and the power of the hormones at play.
I hope it works out for you