CLW, It doesn't matter what we say to you or whether only 2 people have said he could be faithful or whether we think "once a cheater, always a cheater." Or whether we think porn is acceptable or cocaine, or whether 4 times in one month is too much, or only happened that one month or is related to alcohol or whether the girl he cheated with has a bad reputation or whether she was seduced by your husband or whether she took advantage of him. Or whether his sponsor relapsing drove your husband to drink, use porn, snort coke, and cheat on you. Or whether his having his dream job will cure the stress that caused the relapse...
What matters is what YOU are willing to tolerate in your marriage. You get to decide where you draw the lines.
That includes whether you have a houseguest for a year. You have the ability to tell her that it isn't working out for your family and she will have to stay somewhere else.
You sound bubbly, sweet, naive, and trusting. And very forgiving. All good qualities. We are merely trying to encourage you to be realistic about what you're living with. He's not your BFF if he put another woman between you. He's NOT your bff if he uses cocaine and leaves you in charge of your little girl. He's not the love of your life if he does these awful things to you.
It took me about 12 years to realize this about my (former) BFF, sweet hubby, love-of-my-life. He was a disaster as a husband (even though he was cute and my chidlren love him) and he was taking me down with him.
Your situation may be able to be turned around. I hope so, but please be aware and put yourself and your daughter's well-being first. And that includes well-being that is separate from being in love, appearing happy, and wanting an intact family. My well-being was greatly enhanced when I became honest about what I was dealing with.
I hope you can hear what we are saying to you. We all speak from experience.