I think if you go to your husband now and tell him he has an addition and needs to get counseling, he is not going to be receptive at all.
At this point I think you need to sit down with your husband and in a non-confrontational and non-argumenative way tell him that he is making a decision about the kind of father and husband he wants to be - he needs to understand that his decision to spend time on the computer instead of with his family is a conscious decision. Let him know that you have chosen to be a present parent who is going to have fun with your daughter and that you hope he chooses to joins you.
After that you need to live your life and have fun with your daughter. Hopefully, the computer is in a room where you can close the door, and "forget" he is in there.
Cook dinner for you and your daughter and if he wants to eat he'll come out of the room. If he doesn't he can make something for himself later.
If your daughter is wondering where he is and why he's not around you should tell her to ask him that question - he needs to explain to her why he's not spending time with her. It is not your job to make excuses for him, or should you criticize him for his choice. Hopefully, explaining to her face-to-face why he's not playing with her will help him see how important he is to her.
You can not do everything around the home on your own, so if he chooses not to help with the lawn then you may need to hire a service. If he won't help fix things around the house, then a handy-man may need to be hired. If you work full time and he's not helping keep up the house, then a cleaning service may need to come every couple weeks. If he sees that his absence is costing money, this may motivate him to be more helpful (I know this would be a big motivator for my husband).
Plan fun things with your daughter. Tell your husband that you are going to the zoo (for example) tomorrow and you are leaving at this time and you hope he chooses to join you. Tell him that if he is on the computer when you plan to leave at such-and-such time then you will go without him and leave at your set time without a word or a reminder (he'll probably see reminders as "nagging").
Hopefully when the "nagging" stops and he realizes he is making his own decisions, he will make the right ones. If he still doesn't choose to spend time with you and your daughter then you may want to talk to him about taking a break from the computer, addiction or divorce.
I know how you feel, my husband spent more time on the computer than I would like and this approach worked for us. Now he does his computer time after the kids are in bed, which is fine with me b/c I don't like to share the remote :) And we talk before bed or at dinner. I wish you all the best.