Agony aunt, Andrea Moon:- Is it selfish to introduce someone new?

A: Unfortunately 42 per cent of UK marriages reportedly end in divorce, so you’re not alone. It can be frightening to open yourself up to dating again, especially when there are children involved. 
Are you really ready as there will ultimately be a chance of rejection ?
I would advise making more ‘me time’ first whether it is for drinks or coffee with friends or nights out. There are classes to attend that will give you a chance to find out what interests you rather than just being part of a couple. You have been on your own with the kids for the past three years and you’re still here, so you can survive. 
Give yourself some credit. You are still young and deserve to have a loving partner. 
I am glad to hear you have continued to allow access to your ex as it does help a child to maintain relationships and foster trust in future life. The key is to avoid ‘bad-mouthing’ your ex or his new wife. 
It’s hard to remain civil, so, well done! 
Let your children know although they will always have their dad, you would like to move on. That way they can also be somewhat emotionally prepared.
Try internet dating and talking to people before dating, rather than interrogating the first man you see as a potential husband. It really is a numbers game, you will no doubt have a few nice but unfruitful dates before finding someone that you click with. Always let someone know where you are going. 
Although it is better to be truthful about having children, please ensure you have some sort of future before introducing a new man. It is unfair and awkward to trail a string of men through their lives, before an abrupt disappearing act, as well as unsafe. 
If someone has not previously had children it can be difficult to embrace a parenting role, so please don’t expect insta-Dad. If you ever do have any concerns about letting a new man into your life, you could contact the police as part of Clare’s Law. Be positive and confident, you deserve a new life.