Focus on the three things you are handling right now (don't forget your spouse). Don't learn the hard way about overextending yourself. Handle what's in front of you first. Make yourself acknowledge that now is not a good time for side projects and freelancing. A day job and two young children should take all your time.
New babies trigger a 'nesting' overdrive mode in parents. On top that you're facing turning 30. Take a step back and tell yourself that you are a good parent and provider. A good job and a healthy family is plenty to ask for.
Another good coping method is a notebook. Write down all the ideas and side projects just to get them out of your head. A good time for this is 30min before bed. It helps you stop the spinning gears and get to sleep.