Wow, a lot of really great answers here. Not sure if one more will help, but here I go anyway. First of all, you are not being selfish to want some time to yourself and your husband, away from kids. I have a friend who nanny's, has a little boy and is expecting her second. Nannying all day means that she gets home, and LOVES her son, but has set an early bedtime for him so that she can have some time just to herself and her husband; adults only time. (She is getting ready to start looking for a different job.)
Secondly, after all that has happened, wow! It is no wonder you feel like you've lost the spark. I am SO sorry about your sister! In the midst off all that is happening, feeling romantic and alive and fun is hard.
Have you talked to your husband about evening time? Why are you in the bedroom, while he watches TV? It is really important to do things together; and I don't mean that you have to do the same things all the time, but while he is watching TV, you could be sitting next to him reading a book, or scrapbooking, or whatever it is that you like to do! Sometimes the two of you should sit next to each other on the couch and watch a dvd. Ask if he can brush your hair; you can give him a shoulder rub, or just hold his knee (guys like it when you hold their knee and run your fingers up and down their leg).
Wanting to spend time with your husband and not your sons once in a while is not wrong. You married your man because you like him, right? Once a month, have a date night. Whether there is a friend you can exchange free babysitting with, or whether your kids get to stay up late one night in their room (see Rebecca H. below), spend time together. Have a date night twice a month, or once a week, if needed! Just spend quality one-on-one time together. And COMMUNICATE! I don't know if you have talked with your sweetheart about all of this, but open up and do so. No one is a mind reader, and he may not know you feel like this. In fact, you might discover that he feels the same way!
For yourself, take the time to have a bubble bath, or ask your husband if he can watch the kids one evening and you go hang out with some friends, or just go on a solo shopping trip. Heck, make it a Saturday event; save your shopping so that when you do go, you can be gone for hours, and then make it a special event. Take the time to browse through your favorite aisles (even if you don't buy anything from them). Get yourself a special coffee, or a shake, or go out for lunch. I do this a couple times a year (the Saturday shopping trip), and by the time I get home I feel so refreshed!
Are you a Christian? If so, make time to focus on God and read His word, go to Church on Sunday and interact with others who believe as you do. Talk to God continuously, as if you were talking on the phone to a close friend (which is how God wants us to view Him anyway). You would be amazed how a close and intimate relationship with God makes everything else right and fall into place.
Hope everything works out!
God bless!
M.