I would recommend making the websites which you host on the VPS go through Cloudflare and that's a perfect solution for you a while. If the ones who attack you know the IP address of the VPS, then ask you VPS hosting company to give you a new IP address because you want to stay away from attackers. Once you get a new IP address, the ones who are attacking you won't know the IP address of your VPS, and it will take them a while to find out your new IP address.
At the same time, as soon as you get the new IP address, open a free account with Cloudflare and make all your websites go through Cloudflare. This will involve updates on your domain's DNS records, so as your public records and IP address will become Cloudflare's DNS records and IP address. So when the hackers attack you next time, they will direct their DDOS attack to the Cloudflare's IP address, and Cloudflare will handle that for you perfectly. In this way, the attackers will never find out the real IP address of your websites (and VPS server), and Cloudflare will face and solve the DDOS attacks for you.
Please note that Cloudflare has a free plan, and you don't necessarily have to pay them money for the protection that I wrote you above. Also, I am bringing Cloudflare as an example, so as I have been using them for the same exact purpose and a few others for several months, and I really like them. Anyway, I would encourage you to look for other similar companies as options, so as there are many on the market nowadays.