One of the best things you can do for your kids as a mom is to have a good relationship with your husband. It's very tough when the kids are young since they want you all the time and you feel all used up by the time you get to your husband. But kids learn about what a marriage partner should be and what a marriage should be based on how their parents are with eachother. When my kids were younger my husgand and I had some very tough times. He's a NYPD sergeant and often works long hours (post 9/11, the 2003 black out, holidays, any kind of emergency) and was pretty selfish for many years. The coldness of our relationship and the arguments took their toll on our kids. They had some very rough times that I know were in part due to the conflict and coldness at home. Home is supposed to be the safe place for kids where they escape the stuff of the world and feel nurtured.
God has been good and we've been through a lot of stuff over the past 3 years - family illnesses and death, auto accidnets, etc - but it has all served to work in our marriage to make it stronger and to mature us both - particularly my husband. He is now a different person than he was 4 years ago - only by God's grace. Our marriage is stronger than it ever was and our kids are in a better emotional place now than they've been in years. (They are 15 and 12.) Do whatever you can to carve out time for your marriage - nurture it and even if he's not being the husband he could be or you'd like him to be, be the best wife you can and watch how he responds. Men respond to respect, women to love. That was a huge thing I needed to learn.
As for your kids being "clingy" my kids have always been the same way. My 15 yr old will still, on occasion, ask me to lay down with her when she falls asleep. We all like to lay all over eachother on the couch while we watch TV - which is why we bought a sectional - so we all fit! My 12 yr old son still likes me to lay down next to him as he falls asleep many nights - less all the time and I know that it's coming to an end. He plays football, baseball and basketball and is a tall good looking kid but still loves his mom and will give me big hugs and wants to put his head on my shoulder - as long as no one is looking. ;o)
I do think it's normal for kids to want to be with their mom - but yes it's exhausting. I learned to multi-task. When they wanted me in the bathroom while they bathed I'd read the newspaper, the Bible or a book. When they all wanted to laydown together at bed time the older one would come in to the younger one's room and we'd lay on the floor. I'd pray with them as they fell asleep and I'd walk the older one to her bed while she was sound asleep!
These days are fleeting and before you know it they're in high school, talking back, slamming doors and telling you they can't wait until they're 18 and can move out. (hahaha!) Then 20 minutes later they recall all those nights that you cuddled them to sleep and they come, hug you and tell you they're sorry for being a brat. ;o)
It's a season of your life that will pass - I promise. Take your vitamins, get as much sleep as you can - relax your housekeeping standards (I can't even tell you how much mine have "relaxed" over the years!) and realize that you'll blink and they'll be grown up and you'll look back on these exhausting years as sweet wonderful times. ;o) You can always vacuum or mop the kitchen floor another time - but your kids will only be at this point in their life now. There are no do-overs and you get one shot with your kids. You can have an immaculate home once they're grown up.
Hug those kids, savor the moments and give your DH a big wet smooch - then go take a nap! God luck mama!