You sound like a very generous person... a fact that has made it easy for this "friend" to take advantage of you. Real friendships require an even measure of give-and-take from both parties. This relationship is much too one-sided to work. You give, she takes.
Look at it this way: you're different people who have different habits, priorities, schedules, opinions, and needs. This woman's "friendship" offers no fulfillment for you in any of these areas. Not that you need it, but you have my permission to move on.
We learn from childhood that "everyone needs to get along and be friends." It's a nice sentiment, but the reality of it is that some people are just too different to truly be friends, and though no one ever said so in Kindergarten, that is OK. You don't need to be rude or insensitive to her, but if moving on is truly what you want (and need), then it is time to let her know that you are doing so. The next time she calls, try something like, "Hi Jeanine. I'm glad you called because I need to talk to you. I hope that our sons can remain friends, but in truth, I just don't feel close enough to you to share with you the way you share with me. I don't mean to hurt your feelings, but I don't want to encourage this relationship any longer." Trust me, the conversation can be awkward, but it leaves no doubt as to your intentions.
Be strong. Good luck. God Bless.