Hi Kristy...
Well dear, I don't read music, so sheet music does me no good :no: ..The way I learn a new song is to listen to it...repeatedly and sing along as I learn...
Some I am just familiar with and as I try to sing em find I can feel my way through them...Others, (the ones totally new to me) I must play repeatedly. Usually I put those in my car and just keep restarting them..I work on them 3 or 4 lines at a time, until I become familiar enough with em to get all the way through.. 
Helps pass the time while driving too..I wouldn't say I actually memorize them, but more familiarize my self with them.
I always sing in the car...I find it's a great way to become familiar with songs I want to learn. Do you have any karaoke disks? Many of them have practice tracks as well as performance tracks. Sound Choice Star Series are good for that, but there are some others that also provide this feature.. Look on ebay...You can buy complete sets of karaoke disks there for a small price ... ...
You might also hit a few yard sales and try to pick up some cds or old cassette tapes to find some new material..I have payed as little as 25 cents for cassettes at yard sales..If it's country music you're interested in learning more of, listen to cmt on television...Same for the other genures, respectively.. There are alot of free tunes on the web too...The music you're not singing is so much more relaxed than what you are used to...My cable network also has music stations..which is another good oportunity..I would listen and choose songs first, making a list of things you might like to try, then go in search of backings and lyrics...For karaoke we don't need sheet music too much...
(or maybe that's just my narrow opinion cuz I couldn't read it if I had it..) 
I would think show tunes and standards would be the natural choice for you with your training..But hey anything goes..Just reach out for whatever genure makes you feel good to sing..I sure enjoyed your out of the box posts last week...and look forward to more..
Actually, you listen to a ton of music right here on SS...Don't you ever just think, gee I'd love to give that one a go? So play it repeatedly and learn it from someone elses rendition if need be....Then go in search of the backing..Lyrics are readily available on the web..
I always sing off my own disks at karaoke, and I highly recommend that to all..The arrangements can vary greatly. It's always less to worry about when you know how the song will play out....Helps alot with the confidence factor knowing you will probably make it through the song ok, cuz you have practiced it just like it's going to happen..
Reading your exact question again, I guess I have rambled on here, but I gave you a few different ideas...You have my email, I think, so write to me. Maybe I can help ya out if you tell me what songs you are hunting..
I will be happy to help you find songs..
One more Ramble....There is a site where you can play karaoke music and the words (just like at karaoke) to over 20,000 songs on the web...The cost is 9.95 a month...They have the best brand names of disks and on many of those you can play a demo singer also to help you learn the songs. I use it to hunt possible new song choices sometimes, or to compare backings, or to check basic karaoke availability..I won't list it here cuz I don't know if we are allowed but will happily share the link with you when you email or message me again..
Hope some of that helps you...
ps. Don't know if you have a karaoke machine or not. But just to give you another idea, I bought my first one at a pawn shop for 50.00...I still have it, ...That one and 4 others now, . Get yourself a karaoke machine and a cdg or two and see what developes...