I’m six years post-split and three years divorced. My ex left for OW and they are now married with a young baby.
The first two years were the hardest. I would not wish those years on anyone. Take all the help you can get. Self refer on the NHS to get some counselling. If you have private health care through work, see what provision they make for therapy and use them. You can talk to your friends but you will find they all react differently depending on how they feel about their own relationships. Having someone who is unbiased and able to help you see the light at the end of the tunnel really helped in the early day.
Know those days are hard and do not make any hard and fast decisions in those early days. I negotiated to stay in the marital home for two years post split and it was the best thing I ever did. It gave me and the kids some stability and for me the space to think and plan my next move. Just before the two years were up, I was ready to move on and was in the right headspace to buy the right property for me and my DCs. And buying my current place myself is still the best thing I ever did, we are very happy here.
Do not jump into any serious relationships in the first two years. Your judgement is seriously impaired even if you think you are fine and the number of women (including myself) who have made this mistake on these board make really worrying reading! Another man will not save you or make the situation better. You have to do that yourself.
There will be times when things are just shit, accept that, and grieve the relationship properly. Use this as a opportunity to do stuff for yourself and find yourself and your passions. The last six years have seriously been some of the best of my life and for most of it, I have been single. I have dated, had lots of fun but ultimately, the best love I have found in these six years is for myself and for the girlfriends (both old and new) who have supported me through everything. Definitely make new girlfriends. I have made amazing new friends the last few years - some are single, some not, some are childless, by choice and also not. But we all met through life events and clicked and we go out, have fun and support one another. 
Be civil to your ex, your children will thrive if you are able to maintain a supportive, co-parenting relationship with your ex. And overall, it will make your life easier if you both can get along. Sometimes it’s so hard but go home and scream/cry into a pillow. And things will get easier. My DCs now have a little sister the love dearly and it’s hard to hate in the face of that.
Good luck for all those going through this. You’ve got this!