Oh A....I was in your shoes as far as the guilt. My parents are divorced and for as long as I can remember, it has been my mom and me. I am an only child and at the time, I had an almost 3 year old and was due to have my second son.
In our case, my husband got a job promotion that meant us moving from MD to upstate NY. I didn't know what to do because like you, I knew my mom was going to freak...and while she held it together better than I expected, she DID freak to a degree but what could I do. We had to do what was best for our family at the time and that meant moving.
I spent the first year or so coming home about every 6 weeks and my grandmother did die about a year after I moved, but again, what could I do? That was the opportunity we had at the time and we needed to take it. You guys sound the same...like you need an opportunity to get out on your own again and that isn't working where you are.
I will tell you my mom has since flown for the first time in her life - and many times now in the past 6 years or so. She comes for every birthday party and if we aren't there for Thanksgiving or Christmas or going to visit the in-laws, she comes here.
Right now we are trying to decide where to plant our roots and wherever that ends up being, my mom is going to live as well.
You make it work. While my mom misses seeing us every week, she understands it was what was best for our family. THEY are our priority now. Just remember, if she does give you a hard time, you need to be loving but FIRM. Tell her you love her, you will miss her horribly, but that you don't have any where else to turn right now. If the guilt trip gets to be too heavy, put a stop to it. Tell her this is very hard for you as it is and that she is not helping and WALK AWAY. I'm not saying be rude to your mom but your mom doesn't have the right to treat you horribly either when what are you doing to be mean? You obviously love your mom and don't want to hurt her.
I wish you the best. I know how tough this is.