If I overstayed my tourist visa, am I going to have problems with immigration if I live with my boyfriend before marrying him?

Until you are married and apply for adjustment of status on the basis of marriage, you are unlawfully present and subject to removal. You should try to get married as soon as possible and then file for adjustment of status.

You will not have any problems with the Immigration Service for living together but you will certainly have problems for being unlawfully in the US. If you are seriously considering to get married, you should consult with an immigration lawyer.

US Immigration Service will not hold it against you if you live with your future husband before getting married. The Service's only concern is whether your marriage is real or just to get you a green card. If you entered the U.S. legally, later got married, and your U.S. citizen husband files papers petitioning the U.S. Government for your permanent resident status in the U.S., you can get a green card - provided that a) the marriage is real; b) your husband can show to USCIS that you will not become a public charge (i.e. that he can support you financially; if he does not have enough income and/or assets, you will need a co-sponsor who does); c) you don't have criminal convictions, past violations of immigration laws, present a threat to the national security, or cannot be admitted to the U.S. for some other reason. The length of time you overstayed your visa before you get married does not matter.

Your current status as an "Overstay" normally will not prevent you from having your US Citizen spouse (currently your "boyfriend") ultimately file the concurrent spousal adjustment of status (LPR) petitions required to ultimately provide you with a family-based immediate relative I-551 "green card" once you are actually married. How long you remain an "Overstay" (after having initially entered in "lawful status") with the inherent risk of being detained by ICE at any given point in time is a decision that only you can make. Immigration does not care if you live with your boyfriend prior to marriage, but does have existing Regulations that could affect your options in the future based on the time that you remain out of status in the US beyond the period that you were initially authorized to remain at the time of your initial entry in B-2 (Visitor for Pleasure) classification. You should consult with an experienced immigration attorney to guide you and your future husband through the "green card" process which is both complex and lengthy in duration. Under no circumstances should you depart the US before consulting with such an attorney since you would trigger the 3/10 year bars under IIRAIRA upon such a departure (which would complicate your future options significantly).

You can marry and apply for your green card right away. There is no need to wait. I would recommend doing the wedding with both families present. It will look better and make the process easier (especially at your green card interview).

It's not required that you live together before you get married and submit your application for adjustment of status with USCIS, but it can serve as evidence that you will get married in good faith. However, until you are married and file your application, you are at risk of being picked up and placed into removal proceedings by the authorities. It's probably best if you can get married as soon as possible and start the process for your residency status.