First, I want to echo what others have said... my deepest condolences on the loss of your husband. Hopefully church is a good place to be, where you yourself can find comfort and hope.
My name is W., and I'm a 31-year old pastor with an almost-3 year old. I'm so glad you're bringing your kids to church! It's so important for them to get the cadences of worship life into their hearts and minds as little ones. So many people say they'll wait until their kids are "ready" -- but for many families, that fabled time never arrives. Church is also the only place in society where kids see all generations interacting together -- and it's so good for them to have a community, especially if yours is a church where people take time to learn your kids' names.
That said, our congregation is almost 20% kids, and I see families facing these challenges every week. Speaking for myself, I'd rather preach with noisy kids than have museum-silent church. I imagine most pastors feel the same way. Jesus said, "Let the little children come to me, and do not hinder them." This is important stuff!
A few suggestions... have 3 bags of Church-only toys (our Church has bags with finger puppets, clipboards that you can attach papers or kids' bulletins to color, seasonal stickers, etc.) I say 3 bags so you can rotate through and they remain special; and Church-only so that they maintain their appeal.
Also, many families automatically sit in back (the "bleacher seats") -- where it's hard to see the candles, flowers, choir, organ, and action. It's counter-intuitive to sit up front, but might hold their attention and give you opportunities to point out symbols and what the people are doing.
Teaching kids some of the responses is helpful -- the words to songs that are used often, or if you're in a liturgical tradition, you have lots of things that are spoken each week (the Lord be with you -- kids motion with hands and say, "and also with you"). You can even teach them some sign language bits so they can "move" with the liturgy (like the first words of the Lord's prayer, or make the sign for Love or Jesus whenever they hear it). Or motions like making the sign of the cross (God be in my head/thinking, heart/feelings, and shoulders/strength/ doing). (Also, if the music is jazzy, you can have some shakin-eggs (buy them at a music store for $1.50 each) so the kids can contribute to the music. Collect them when the music ends.)
Another option is to bring something for them to draw or color as their "offering," which they put in the offering plate when adults put money in the plate. Talk to your pastor about whether there is a place these pictures could be posted, and let your kids know how God smiles when they make offerings of their time and talents. This could be a growing ministry for your congregation to value the gifts kids bring -- and the tellers will enjoy seeing the offerings over the weeks!
You can also do some things at home, like having a nightly blessing. My little guy sometimes even gives me a blessing as I put him to bed... he wants to be a part of it all.
Blessings to you and your kids. What you're doing makes a big difference -- giving your kids a community and hearing about God's unconditional love for them. It's Good News!
Peace and hope throughout your journey!