Reacting
Get some space away from your ex. Tell him/her nicely that you are already out of this relationship and prefer him/her to leave you alone. Avoid accepting phone calls, text messages from your ex, or replying his/her emails. This helps you to clear your thoughts and being able to move on with your current partner.
Schedule some activities with your friends. This is a good way of keeping yourself busy and a good way to temporary keep negative emotions away. Hang out with your own friends. Spend more time with your current partner. Avoiding the ex and the mutual friends, if you find it hard not to think of your ex at that moment.
Change your environment. Put on light, classical or jazz music at home and relax in it. These gives you a calming effect which also makes him/her, into a more sentimental person, allowing yourself to express your feelings, cry over it, but cease to think about it later. On the other hand, go travelling or relocate yourself in another place, it helps you in recovering.
Do not over react towards this breakup. Do not do something stupid just because you are temporary upset. Do not do things that cause harm to yourself, or you current partner.
Find ways to heal your heartbreak. Express your thoughts through writing or painting. Read articles. Read articles written by others’ who share their experiences could help. Read motivation books and get inspired. You may also write about your heartbreaks and share it online to help others.