So, I have a blog at domain.com. This blog is HTTP-only because I would gain almost nothing from adding SSL support. I have a web service now that I want to enable SSL support on that runs on the same server and IP address as my blog. I got it all working pretty easily, but not if I go to https://domain.com I will see a huge warning about an SSL certificate error and then if I click ok through the warning, I'll see the web service with SSL support, not my blog. My biggest fear with this scheme is Google indexing an HTTPS version of it and penalizing my blog because the content between the two doesn't match. How can I somehow for my blog's domain to either not serve anything on HTTPS, or to redirect back to my HTTP blog, or to serve my blog, but with an invalid SSL certificate? What can I do, preferably without buying another dedicated IP for my website? 
How can I prevent HTTPS on another domain from wrongly showing on my HTTP-only domain?
https;google index;http