Welcome Lihle,
I too am a widow, it's been just over 3 years for me. I don't have kids, so for me my work/business has been my solace outside of my relationship with God. Please don't feel you have to grieve on someone else's timeline. But it's good that you are feeling like you want to start up a social life again. Grief really can just suck you dry.
I don't have good advice on starting up with a social life again. I do bible studies with groups of women. I LITERALLY don't know any single Christian men in my town, so I figure if God wants me to meet someone he'll move me or someone into my life. (I'm actually praying for this miracle to happen... as possibly shallow as that may sound. He promises to meet ALL of our needs.)
Anyway, I know very well how absolutely hard this is. I'm glad your kids have some outlet. Are you going to church, having that fellowship is nice too. Are you working? Is that something you could do while the kids are in school? I know it is a fulfilling thing to feel like you have a purpose.
If you would like to PM me, I'd be happy to chat more openly. Sometimes this place - CC - feels far too public for me.
God bless you sister, praying for you!